Herbicidal cyclohexane-1,3-dione derivatives

ABSTRACT

Compounds of the formula ##STR1## wherein: R 5  is a bicyclic aryl or nitrogen-containing heteroaryl ring system such as naphthyl, quinolyl, isoquinolyl or tetrahydroisoquinolyl, optionally substituted by a wide variety of groups; 
     R 4  and R 1  are preferably hydrogen but may be other groups and 
     R 2  and R 3  are selected from alkyl, haloalkyl, alkenyl, haloalkenyl and alkynyl, show high general grass-killing activity with good selectivity to many broad-leaf crops and in some instances selectivity to small-grain cereals. Processes for the preparation of compounds of formula I, intermediates in the preparation of compounds I and the herbicidal properties of compounds I are described.

This invention relates to organic compounds having biological activity and in particular to organic compounds having herbicidal properties and plant growth regulating properties, to processes for the preparation of such compounds, to intermediate useful in the preparation of such compounds and to herbicidal compositions and processes utilizing such compounds and to plant growth regulating compositions an processes utilizing such compounds.

The use of certain cyclohexane-1,3-dione derivatives as grass herbicides is known in the art. For example, the "Pesticide Manual" (C R Worthing Editor, The British Crop Protection Council, 6th Edition 1979) describes the cyclohexane-1,3-dione derivative known commercially as alloxydim-sodium (methyl 3-[1-(allyloxyimino)butyl]-4-hydroxy-6,6-dimethyl-2-oxocyclohex-3-ene carboxylate) and its use as a grass herbicide. This compound is disclosed in Australian Pat. No 464 655 and its equivalents such as U.K. Pat. No 1 461 170 and U.S. Pat. No 3,950,420.

More recently, at the 1980 British Crop Protection Conference ("1980 British Crop Protection Conference--Weeds, Proceedings Vol 1, Research Reports", pp 39 to 46, British Crop Protection Council, 980), a new cyclohexane-1,3-dione grass herbicide code named NP 55 (2-N-ethoxybutrimidoyl)-5-(2-ethylthiopropyl)-3-hydroxy-2-cyclohexen-1-one) was announced. This compound is disclosed in Australian Pat. No. 503 917 and its equivalents.

It has now been found that a new group of cyclohexane-1,3-dione derivatives which have a 5-naphthyl, 5-(cycloalkyl substituted azinyl) or 5-(benzo substituted azinyl) substituents exhibit particularly useful herbicidal activity.

Accordingly the invention provides a compound of formula I ##STR2## wherein:

A, G, D and E are independently selected from CH, N and N-Z wherein Z is selected from oxygen and the group --YAn wherein Y is selected from C₁ to C₆ alkyl and benzyl and An is an anion selected from halide, tetrafluoroborate, methosulfate and fluorosulfate, and provided that no more than three of A, G, D and E are selected from N and N-Z and no more than one of A, G, D and E is selected from N-Z;

W is a saturated or unsaturated hydrocarbon chain containing from two to five carbon atoms when one or more of A, G, D or E is selected from N or N-Z;

W is an unsaturated hydrocarbon chain containing four carbon atoms when A, G, D and E are all CH;

X, which may be the same or different, and X¹, which may be the same or different, are independently selected from the group consisting of: halogen; nitro; cyano; C₁ to C₆ alkyl; C₁ to C₆ alkyl substituted with a substituent selected from the group consisting of halgen, nitro, hydroxy, C₁ to C₆ alkoxy and C₁ to C₆ alkylthio; C₂ to C₆ alkenyl; C₂ to C₆ alkynyl; hydroxy; C₁ to C₆ alkoxy; C₁ to C₆ alkoxy substituted with a substituent selected from halogen and C₁ to C₆ alkoxy; C₂ to C₆ alkenyloxy; C₂ to C₆ alkynyloxy; C₂ to C₆ alkanoyloxy; (C₁ to C₆ alkoxy)carbonyl; C₁ to C₆ alkylthio; C₁ to C₆ alkylsulfinyl; C₁ to C₆ alkylsulfonyl; sulfamoyl; N-(C₁ to C₆ alkyl)sulfamoyl; N,N-di(C₁ to C₆ alkyl)-sulfamoyl; benzyloxy; substituted benzyloxy wherein the benzene ring is substituted with from one to three substituents selected from the group consisting of halogen, nitro, C₁ to C₆ alkyl, C₁ to C₆ alkoxy and C₁ to C₆ haloalkyl; the group NR⁵ R⁶ wherein R⁵ and R⁶ are independently selected from the group consisting of hydrogen, C₁ to C₆ alkyl, C₂ to C₆ alkanoyl, benzoyl and benzyl; the groups formyl and C₂ to C₆ alkanoyl and the oxime, imine and Schiff base derivatives thereof; or two of X¹ on the same carbon atom may form an oxo group;

R¹ is selected from the group consisting of: hydrogen; C₁ to C₆ alkyl; C₂ to C₆ alkenyl; C₂ to C₆ alkynyl; substituted C₁ to C₆ alkyl wherein the alkyl group is substituted with a substituent selected from the group consisting of C₁ to C₆ alkoxy, C₁ to C₆ alkylthio, phenyl and substituted phenyl wherein the benzene ring is substituted with from one to three substituents selected from the group consisting of halogen, nitro, cyano, C₁ to C₆ alkyl, C₁ to C₆ haloalkyl, C₁ to C₆ alkoxy and C₁ to C₆ alkylthio; C₁ to C₆ alkyl sulfonyl; benzenesulfonyl; substituted benzenesulfonyl wherein the benzene ring is substituted with from one to three substituents selected from the group consisting of halogen, nitro, cyano, C₁ to C₆ alkyl, C₁ to C₆ haloalkyl, C₁ to C₆ alkoxy and C₁ to C₆ alkylthio; an acyl group; and an inorganic or organic cation;

R² is selected from the group consisting of: C₁ to C₆ alkyl; C₂ to C₆ alkenyl; C₂ to C₆ haloalkenyl; C₂ to C₆ alkynyl; C₂ to C₆ haloalkynyl; substituted C₁ to C₆ alkyl wherein the alkyl group is substituted with a substituent selected from the group consisting of halogen, C₁ to C₆ alkoxy, C₁ to C₆ alkylthio, phenyl and substituted phenyl wherein the benzene ring is substituted with from one to three substituents selected from the group consisting of halogen, nitro, cyano, C₁ to C₆ alkyl, C₁ to C₆ haloalkyl, C₁ to C₆ alkoxy and C₁ to C₆ alkylthio;

R₃ is selected from the group consisting of: C₁ to C₆ alkyl; C₁ to C₆ fluoroalkyl; C₂ to C₆ alkenyl; C₂ to C₆ alkynyl; and phenyl;

R₄ is selected from the group consisting of: hydrogen; halogen; cyano; C₁ to C₆ alkyl; and (C₁ to C₆ alkoxy)carbonyl;

n is 0 or an integer chosen from 1 to 3; and n¹ is 0 or an integer chosen from 1 to 5.

When in the compound of formula I X is chosen from the groups formyl and C₂ to C₆ alkanoyl and the oxime, imine and Schiff base derivatives thereof, the nature of the oxime, imine and Schiff base derivatives is not narrowly critical. Although not intending to be bound by theory, it is believed that in the plant the (substituted) imine group may be removed to give the corresponding compound of formula I in which X is formyl or C₂ to C₆ alkanoyl. Suitable values for the groups formyl and C₂ to C₆ alkanoyl and the oxime, imine and Schiff base derivatives thereof include groups of the formula --C(R⁷)═NR⁸ wherein R⁷ is chosen from hydrogen and C₁ to C₅ alkyl, and R⁸ is chosen from hydrogen, C₁ to C₆ alkyl, phenyl, benzyl, hydroxy, C₁ to C₆ alkoxy, phenoxy and benzyloxy.

When in the compound of formula I R¹ is chosen from acyl the nature of the acyl group is not narrowly critical. Although not intending to be bound by theory, it is believed that when R¹ is acyl the acyl group may be removed in the plant by hydrolysis to give the corresponding compound of formula I in which R¹ is hydrogen. Suitable acyl groups include: alkanoyl, for example C₂ to C₆ alkanoyl; aroyl, for example benzoyl and substituted benzoyl wherein the benzene ring is substituted with from one to three substituents chosen from the group consisting of halogen, nitro, cyano, C₁ to C₆ alkyl, C₁ to C₆ haloalkyl, C₁ to C₆ alkoxy and C₁ to C₆ alkylthio; and heteroaroyl, for example 2-furoyl, 3-furoyl, 2-thenoyl and 3-thenoyl.

When in the compound of formula I R¹ is chosen from an inorganic or organic cation the nature of the cation is not narrowly critical. Although not intending to be bound by theory, it is believed that when R¹ is a cation the cation may be removed in the plant to give a compound of formula I wherein R¹ is hydrogen. Suitable inorganic cations include the alkali and alkaline earth metal ions, heavy metal ions including the transition metal ions, and the ammonium ion. Suitable organic cations include the cation R⁹ R¹⁰ R¹¹ R¹² N⁺ wherein R⁹, R¹⁰, R¹¹ and R¹² are independently chosen from the group consisting of: hydrogen; C₁ to C₁₀ alkyl; substituted C₁ to C₁₀ alkyl wherein the alkyl groups is substituted with a substituent chosen from the group consisting of hydroxy, halogen and C₁ to C₆ alkoxy; phenyl; benzyl; and the groups substituted phenyl and substituted benzyl wherein the benzene ring is substituted with from one to three substituents chosen from the group consisting of halogen, nitro, cyano, C₁ to C₆ alkyl, C₁ to C₆ haloalkyl, C₁ to C₆ alkoxy and C₁ to C₆ alkylthio.

It should be recognized that when R₁ is hydrogen the compounds of the invention may exist in any one of four tautomeric forms as shown below wherein φ represents the group ##STR3##

The compounds of the invention include: naphthalene derivatives of formula Ia ##STR4## pyridine derivatives of formula Ib and Ic ##STR5## pyridazine derivatives of formula Id and Ie ##STR6## pyrimidine derivatives of formula If ##STR7## pyrazine derivatives of formula Ig ##STR8## triazine derivatives of formula Ih and Ii ##STR9##

Preferred compounds of the invention include those compounds of formulae ##STR10## wherein:

A, G, D and E are independently selected from CH, N and N→O provided that no more than three of A, G, D and E are selected from N and N→O and no more than one of A, G, D and E is selected from N→O;

X, which may be the same or different, and X¹, which may be the same or different, are independently selected from the group consisting of C₁ to C₆ alkyl, C₁ to C₆ haloalkyl, C₁ to C₆ alkoxy, C₁ to C₆ alkylthio; halogen, nitro, sulfamoyl, N-(C₁ to C₆ alkyl)sulfamoyl, N,N-di(C₁ to C₆ alkyl)sulfamoyl, formyl, C₂ to C₆ alkanoyl, and the group of the formula --C(R⁷)═NR⁸ wherein R⁷ is selected from hydrogen and C₁ to C₅ alkyl and R⁸ is selected from hydroxy and C₁ to C₆ alkoxy;

R¹ is selected from the group consisting of: hydrogen; C₂ to C₆ alkanoyl; benzoyl and substituted benzoyl wherein the benzene ring is substituted with from one to three substituents selected from the group consisting of halogen, nitro, C₁ to C₆ alkyl and C₁ to C₆ alkoxy; benzenesulfonyl and substituted benzenesulfonyl wherein the benzene ring is substituted with from one to three substituents selected from the group consisting of halogen, nitro, C₁ to C₆ alkyl and C₁ C₆ alkoxy; and an inorganic or an organic cation selected from the alkali metals such as lithium, potassium and sodium, the alkaline earth metals such as magnesium, calcium and barium, the transition metals such as manganese, copper, zinc, iron, nickel, cobalt and silver, the ammonium ion and the tri- and tetra(alkyl)ammonium ions wherein alkyl is selected from C₁ to C₆ alkyl and C₁ to C₆ hydroxyalkyl;

R² is selected from the group consisting of C₁ to C₆ alkyl, C₂ to C₆ alkenyl, C₂ to C₆ alkynyl, C₁ to C₆ haloalkyl, C₂ to C₆ haloalkenyl and C₂ to C₆ haloalkynyl;

R³ is selected from C₁ to C₆ alkyl;

R⁴ is selected from hydrogen, halogen and (C₁ to C₆ alkoxy)carbonyl;

n is zero or an integer selected from 1 to 3; and

n¹ is zero or an integer selected from 1 to 3.

More preferred compounds of the invention include those compounds of formula I wherein:

A, G, D and E are independently selected from CH, N and N→O provided that no more than one of A, G, D and E is selected from N and N→O;

X, which may be the same or different, and X¹, which may be the same or different, are independently selected from the group consisting of C₁ to C₆ alkyl, hydroxy, C₁ to C₆ alkoxy, halogen, nitro, N,N-di(C₁ to C₆ alkyl) sulfamoyl, and the group of the formula --C(R⁷)═NR⁸ wherein R⁷ is selected from C₁ to C₅ alkyl and R⁸ is selected from C₁ to C₆ alkoxy, or two of X¹ on the same carbon atom may form an oxo group;

R¹ is selected from the group consisting of hydrogen, benzoyl and the alkali metals;

R² is selected from the group consisting of C₁ to C₆ alkyl, C₁ to C₆ haloalkyl, C₂ to C₆ alkenyl and C₂ to C₆ alkynyl;

R³ is selected from the group consisting of C₁ to C₆ alkyl;

R⁴ is hydrogen;

n is zero or an integer selected from 1 to 3; and

n¹ is zero or an integer selected from 1 to 3.

Even more preferred compounds of the invention include those compounds of formulae: ##STR11## wherein:

X, which may be the same or different, are independently selected from the group consisting of C₁ to C₃ alkyl, C₁ to C₃ alkoxy and halogen;

X¹, which may be the same or different, are selected from hydroxy or two of X¹ on the same carbon may form an oxo group;

R¹ is selected from the group consisting of hydrogen and the alkali metals;

R² is selected from the group consisting of C₁ to C₃ alkyl, C₁ to C₃ fluoroalkyl, allyl and propargyl;

R³ is selected from the group consisting of C₁ to C₃ alkyl;

R⁴ is hydrogen;

n is zero or an integer selected from 1 and 2; and

n¹ is zero or an integer selected from 1 and 2.

Particularly preferred values for X include methyl, methoxy and chlorine.

Particularly preferred values for X¹ include hydroxy and the oxo group where two of X¹ on the same carbon atom form an oxo group.

Particularly preferred values for R¹ include hydrogen and the alkali metals.

Particularly preferred values for R² include ethyl, fluoroethyl, allyl and propargyl.

Particularly preferred values for R³ include ethyl and n-propyl.

Particularly preferred R⁴ is hydrogen.

Particularly preferred n is an integer selected from 2 and 3.

Particularly preferred n¹ is zero or an integer selected from 1 and 2.

Specific examples of the compounds of the invention include those compounds detailed in Tables 1a, 1b, 1c, 1d and 1e below.

                  TABLE 1a                                                         ______________________________________                                          ##STR12##                                                                     Com-                                                                           pound A, G,                                                                    No    D, E    (X).sub.n   R.sup.1                                                                            R.sup.2  R.sup.3                                                                              R.sup.4                           ______________________________________                                         10    all CH  all H       H   C.sub.2 H.sub.5                                                                         C.sub.2 H.sub.5                                                                      H                                 11    all CH  all H       H   C.sub.2 H.sub.5                                                                         n-C.sub.3 H.sub.7                                                                    H                                 14    all CH  2,3-(CH.sub.3).sub.2                                                                       H   C.sub.2 H.sub.5                                                                         n-C.sub.3 H.sub.7                                                                    H                                 15    all CH  2,3,4-(CH.sub.3).sub.3                                                                     H   C.sub.2 H.sub.5                                                                         n-C.sub.3 H.sub.7                                                                    H                                 16    all CH  2-CH.sub.3  H   C.sub.2 H.sub.5                                                                         C.sub.2 H.sub.5                                                                      H                                 17    all CH  4-CH.sub.3  H   C.sub.2 H.sub.5                                                                         n-C.sub.3 H.sub.7                                                                    H                                 18    all CH  2-OCH.sub.3 H   C.sub.2 H.sub.5                                                                         n-C.sub.3 H.sub.7                                                                    H                                 19    all CH  4-OCH.sub.3 H   C.sub.2 H.sub.5                                                                         n-C.sub.3 H.sub.7                                                                    H                                 20    all CH  a           H   C.sub.2 H.sub.5                                                                         n-C.sub.3 H.sub.7                                                                    H                                 21    all CH  2,4-(CH.sub.3).sub.2                                                                       H   C.sub.2 H.sub.5                                                                         C.sub.2 H.sub.5                                                                      H                                 22    all CH  2,4-(CH.sub.3).sub.2                                                                       H   C.sub.2 H.sub.5                                                                         n-C.sub.3 H.sub.7                                                                    H                                 23    all CH  2,4-(CH.sub.3).sub.2                                                                       H   CH.sub.2 CHCH.sub.2                                                                     n-C.sub.3 H.sub.7                                                                    H                                 24    all CH  2,4-(CH.sub.3).sub.2                                                                       H   CH.sub.2 CCH                                                                            n-C.sub.3 H.sub.7                                                                    H                                 25    all CH  2,4-(CH.sub.3).sub.2                                                                       H   CH.sub.2 CH.sub.2 F                                                                     n-C.sub.3 H.sub.7                                                                    H                                 26    all CH  2,4-(CH.sub.3).sub.2                                                                       b   C.sub.2 H.sub.5                                                                         n-C.sub.3 H.sub.7                                                                    H                                 27    all CH  2,4-(CH.sub.3).sub.2                                                                       Na  C.sub.2 H.sub.5                                                                         n-C.sub.3 H.sub.7                                                                    H                                 28    all CH  c           H   C.sub.2 H.sub.5                                                                         C.sub.2 H.sub.5                                                                      H                                 29    all CH  2-Br4-CH.sub.3                                                                             H   C.sub.2 H.sub.5                                                                         n-C.sub.3 H.sub.7                                                                    H                                 30    all CH  2-OCH.sub.34-CH.sub.3                                                                      H   C.sub.2 H.sub.5                                                                         n-C.sub.3 H.sub.7                                                                    H                                 31    all CH  3,4-(CH.sub.3).sub.2                                                                       H   C.sub.2 H.sub.5                                                                         C.sub.2 H.sub.5                                                                      H                                 32    all CH  d           H   C.sub.2 H.sub.5                                                                         C.sub.2 H.sub.5                                                                      H                                 33    all CH  e           H   C.sub.2 H.sub.5                                                                         n-C.sub.3 H.sub.7                                                                    H                                 34    A is N  5,6,7-(CH.sub.3).sub.3                                                                     H   C.sub.2 H.sub.5                                                                         n-C.sub.3 H.sub.7                                                                    f                                       rest                                                                           CH                                                                       35    A is N  5,6,7-(CH.sub.3).sub.3                                                                     H   C.sub.2 H.sub.5                                                                         n-C.sub.3 H.sub.7                                                                    H                                       rest                                                                           CH                                                                       ______________________________________                                          Code:                                                                          a 4SO.sub.2 N(CH.sub.3).sub.2                                                  b COC.sub.6 H.sub.5                                                            c 2CH.sub.34-C(NOC.sub.2 H.sub.5)CH.sub.3                                      d 2,3(CH.sub.3).sub.24-C(NOC.sub.2 H.sub.5)CH.sub.3                            e 2,3(CH.sub.3).sub.24-NO.sub.2                                                f CO.sub.2 CH.sub.3                                                      

                  TABLE 1b                                                         ______________________________________                                          ##STR13##                                                                     Com-                                                                           pound                                                                          No    A, G, D, E                                                                               (X).sub.n   (X.sup.1).sub.n.spsb.1                                                                R.sup.2                                                                              R.sup.3                               ______________________________________                                         12    all CH    all H       all H  C.sub.2 H.sub.5                                                                      n-C.sub.2 H.sub.5                     13    all CH    3-CH.sub.3  all H  C.sub.2 H.sub.5                                                                      n-C.sub.3 H.sub.7                     36    all CH    all H       6-CH.sub.3                                                                            C.sub.2 H.sub.5                                                                      n-C.sub.3 H.sub.7                     37    all CH    1,4-(CH.sub.3).sub.2                                                                       all H  C.sub.2 H.sub.5                                                                      n-C.sub.3 H.sub.7                     38    all CH    1,3,4-(CH.sub.3).sub.3                                                                     all H  C.sub.2 H.sub.5                                                                      n-C.sub.3 H.sub.7                     39    E is N    all H       all H  C.sub.2 H.sub.5                                                                      n-C.sub.3 H.sub.7                           rest CH                                                                  ______________________________________                                    

                  TABLE 1c                                                         ______________________________________                                          ##STR14##                                                                     Com-                                                                           pound                                                                          No    (X).sub.n    (X.sup.1).sub.n.spsb.1                                                                 R.sup.1                                                                            R.sup.2   R.sup.3                               ______________________________________                                         40    1-CH.sub.33-Cl                                                                              all H   H   C.sub.2 H.sub.5                                                                          C.sub.2 H.sub.5                       41    1-CH.sub.33-Cl                                                                              all H   H   C.sub.2 H.sub.5                                                                          n-C.sub.3 H.sub.7                     42    1-CH.sub.33-Cl                                                                              all H   H   CH.sub.2 CHCH.sub.2                                                                      n-C.sub.3 H.sub.7                     43    1-CH.sub.33-Cl                                                                              all H   H   CH.sub.2 CCH                                                                             n-C.sub.3 H.sub.7                     44    1-CH.sub.33-Cl                                                                              all H   H   CH.sub.2 CH.sub.2 F                                                                      n-C.sub.3 H.sub.7                     45    1-CH.sub.33-Cl                                                                              all H   Na  C.sub.2 H.sub.5                                                                          n-C.sub.3 H.sub.7                     46    1-CH.sub.33-OCH.sub.3                                                                       all H   H   C.sub.2 H.sub.5                                                                          C.sub.2 H.sub.5                       47    1-CH.sub.33-OCH.sub.3                                                                       all H   H   C.sub.2 H.sub.5                                                                          n-C.sub.3 H.sub.7                     48    1-CH.sub.33-OCH.sub.3                                                                       8-OH    H   C.sub.2 H.sub.5                                                                          n-C.sub.3 H.sub.7                     49    1-CH.sub.33-OCH.sub.3                                                                       8-oxo   H   C.sub.2 H.sub.5                                                                          n-C.sub.3 H.sub.7                     ______________________________________                                    

                  TABLE 1d                                                         ______________________________________                                          ##STR15##                                                                     Com-                                                                           pound                                                                          No      (X).sub.n (X.sup.1).sub.n.spsb.1                                                                 Z       R.sup.2                                                                             R.sup.3                                 ______________________________________                                         50      all H     all H   --      C.sub.2 H.sub.5                                                                     C.sub.2 H.sub.5                         51      all H     all H   0       C.sub.2 H.sub.5                                                                     C.sub.2 H.sub.5                         ______________________________________                                    

                  TABLE 1e                                                         ______________________________________                                          ##STR16##                                                                     Com-                                                                           pound                                                                          No         (X).sub.n                                                                             (X.sup.1).sub.n.spsb.1                                                                     R.sup.2                                                                             R.sup.3                                     ______________________________________                                         52         all H  6-CH.sub.3  C.sub.2 H.sub.5                                                                     C.sub.2 H.sub.5                             ______________________________________                                          The compounds of the invention may be prepared by by a variety of methods      and in a further aspect the invention provides methods for the preparation      of compounds of formula I.

Conveniently the preparation of the compounds of the invention can be considered in three or four parts.

Part A involves the formation of a 5-arylcyclohexan-1,3-dione of formula IX. This reaction may be carried out in a two step process by:

(i) reacting, preferably in the presence of a base, an aldehyde derivative of formula V with acetone (IVa) or an acetone derivative of formula IVb to form a ketone derivative of formula VIa or VIb respectively; and reacting, preferably in the presence of a base, a ketone derivative of formula VIa with a malonic acid ester derivative of formula VIIa or a ketone derivative of formula VIb with a malonic acid ester of formula VIIb, to give an intermediate of formula VIIIa or VIIIb respectively which may be isolated or hydrolysed directly, preferably in the presence of an acid, to give a 5-arylcyclohexan-1,3-dione of formula IX, or reacting, preferably in the presence of a base, a ketone derivative of formula VIa with an alkanoic acid ester of formula VIIc to give a 5-arylcyclohexan-1,3-dione of formula IX;

(ii) reacting, preferably in the presence of a base, an aldehyde derivative of formula V with a malonic acid ester of formula VIIb to give an arylmethylidenemalonate derivative of formula VIc which is in turn reacted, preferably in the presence of a base, with an acetoacetic acid derivative of formula VIId to give an intermediate of formula VIIIc which may be isolated or hydrolysed directly, preferably in the presence of an acid, to give a 5-arylcyclohexan-1,3-dione of formula IX; or

(iii) reacting, preferably in the presence of a base, an aldehyde derivative of formula V with an acetic acid ester of formula IVc to give a 2-arylalkenoate derivative of formula VId which is in turn reacted, preferably in the presence of a base, with an acetoacetic acid ester derivative of formula VIId to give an intermediate of formula VIIIa which may be isolated or hydrolysed directly, preferably in the presence of an acid, to give a 5-arylcyclohexan-1,3-dione of formula IX.

Part B involves the acylation of a compound of formula IX to give a 2-acyl-5-arylcyclohexan-1,3-dione of formula XIII. This reaction may be carried out by reacting a 5-arylcyclohexan-1,3-dione of formula IX with:

(iv) an acid anhydride of formula X in the presence of either an alkali metal salt of the corresponding acid of formula XI or an alkoxide salt of formula XII, wherein M is an alkali metal ion and R is C₁ to C₆ alkyl;

(v) an acid anhydride of formula X in the presence of the corresponding acid of formula XIV;

(vi) an acid halide of formula XV, wherein hal represents halogen, in the presence of a Lewis acid catalyst;

(vii) a mixture of an acid halide of formula XV and the corresponding acid of formula XIV; or

(viii) with an alkali or alkaline earth metal hydride followed by reaction with an acid anhydride of formula X or an acid halide of formula XV.

Alternatively, this acylation reaction may be carried out by:

(ix) reacting a 5-arylcyclohexan-1,3-dione of formula IX with an acid halide of formula XV in the presence of pyridine to give an intermediate O-acyl derivative of formula XVI; and

(x) reacting the intermediate of formula XVI with a Lewis acid catalyst;

(xi) reacting the intermediate of formula XVI with the acid of formula XIV; or

(xii) reacting the intermediate of formula XVI with imidazole.

Part C involves the formation of a compound of the invention of formula I wherein R¹ is hydrogen, that is a compound of formula II. This reaction may be carried out either by reacting a 2-acyl-5-arylcyclohexan-1,3-dione of formula XIII with:

(xiii) an alkoxyamine derivative of formula XVII; or

(xiv) hydroxylamine to give an intermediate oxime derivative of formula XVIII and reacting that intermediate oxime derivative of formula XVIII with an alkylating agent of formula XIX wherein L is a leaving group such as, for example, chloride, bromide, iodide, sulfate, nitrate, methyl sulfate, ethyl sulfate, tetrafluoroborate, hexafluorophosphate, hexafluoroantimonate, methanesulfonate, fluorosulfonate, methanesulfonate and trifluoromethanesulfonate.

Part D involves the formation of a compound of the invention of formula I wherein R¹ is a substituent other than hydrogen.

Compounds of the invention of formula I, wherein R¹ forms an ether, acyl or sulfonyl derivative of a compound of formula II, may be prepared from the corresponding compounds of the invention of formula II by reacting with an etherification, acylation or sulfonylation reagent of formula XX.

Compounds of the invention of formula I wherein R¹ is an inorganic or organic cation may be prepared from the compounds of the invention of formula I wherein R¹ is hydrogen, that is, compounds of formula II, by reacting said compounds of formula II with an inorganic or organic salt. For example, the compounds of formula I wherein R¹ is an alkali metal ion may be prepared by reacting the appropriate compound of formula II with the appropriate alkali metal hydroxide or alkoxylate. The compounds of formula I wherein R¹ is a transition metal ion or an organic cation may similarly be prepared by reacting the appropriate compound of formula II with an appropriate transition metal salt or organic base. Alternatively, the compounds of formula I wherein R¹ is a transition metal ion or an organic cation may be prepared by reacting the appropriate compound of formula I wherein R¹ is an alkali metal ion with an appropriate transition metal salt or organic salt.

Accordingly, in a further aspect the invention provides a process for the preparation of a compound of formula I, as hereinbefore defined, which process comprises:

reacting 2-acyl-5-(aryl)cyclohexane-1,3-dione derivative of formula XIII with an alkoxyamine derivative of formula XVII to give a compound of the invention of formula II or reacting the 2-acyl-5-(aryl)cyclohexane-1,3-dione derivative of formula XIII with hydroxylamine and alkylating the oxime intermediate of formula XVIII with an alkylating agent of formula XIX, wherein L is a leaving group, to give a compound of the invention of formula II; and optionally

reacting the compound of the invention of formula II with a compound of formula XX, wherein L is a leaving group, to give a compound of the invention of formula I.

Certain of the intermediate compounds of formulae V, VIa, VIb, VIc, VId, VIIIa, VIIIb, VIIIc, IX, XIII, XVI and XVIII are novel compounds and therefore in further embodiments the invention provides novel compounds of formulae V, VIa, VIb, VIc, VId, VIIIa, VIIIb, VIIIc, IX, XIII, XVI and XVIII and processes for the preparation thereof.

The structures of the compounds described above are detailed on the following pages wherein φ represents the group ##STR17##

Certain of the intermediate compounds of formulae V, VI, VIII, IX, X, XII, XXI, XIII, XVI and XVIII are novel compounds and therefore as a further embodiment the invention provides novel compounds of formulae V, VI, VIII, IX, X, XII, XXI, XIII, XVI and XVIII, wherein the substituents are as hereinbefore defined, and processes for the preparation thereof.

The compounds of formula I are active as herbicides and therefore, in a further aspect the invention provides a process for severely damaging or killing unwanted plants which process comprises applying to the plants, or to the growth medium of the plants, an effective amount of a compound of formula I as hereinbefore defined.

Generally speaking the compounds of formula I are herbicidally effective against a variety of plants. However, certain of the compounds of the invention are selectively active against monocotyledonous plants, dicotyledonous plants being relatively unaffected by rates of application of the compounds of the invention which are severely damaging or lethal to other plant species.

Moreover, certain of the compounds of formula I are selectively active within the group of monocotyledonous plants and may be used at a rate sufficient to control monocotyledonous weeds in cultivated crops, especially wild grasses in cereal crops. Certain of such compounds of the invention are especially useful in the control of wild grasses such as wild oats and rye grass in crops of cultivated monocotyledonous plants such as wheat and other varieties of cereals.

Accordingly, in yet a further aspect the invention provides a process for controlling monocotyledonous weeds in cultivated crops, especially wild grasses in cereal crops such as wheat, which process comprises applying to the crop, or to the growth medium of the crop a compound of formula I, as hereinbefore defined, in an amount sufficient to severely damage or kill the weeds but insufficient to damage the crop substantially.

The compounds of formula I may be applied directly to the plant (post-emergence application) or to the soil before the emergence of the plant (pre-emergence application). However, the compounds are, in general, more effective when applied to the plant post-emergence.

The compounds of formula I may be used on their own to inhibit the growth of, severely damage, or kill plants but are preferably used in the form of a composition comprising a compound of the invention in admixture with a carrier comprising a solid or liquid diluent. Therefore, in yet a further aspect the invention provides plant growth inhibiting, plant damaging, or plant killing compositions comprising a compound of formula I as hereinbefore defined and an agriculturally acceptable carrier therefor.

Certain of the compounds of formula I exhibit useful plant growth regulating activity. For example, while compounds of formula I are selectively active herbicides against wild grasses in crops of cultivated plants at some rates of application they exhibit plant growth regulating effects in said crops.

Plant growth regulating effects may be manifested in a number of ways. For example, suppression of apical dominance, stimulation of auxiliary bud growth, stimulation of early flowering and seed formation, enhancement of flowering and increase in seed yield, stem thickening, stem shortening and tillering. Plant growth regulating effects shown by compounds of the invention may include, for example, tillering and stem shortening in crops such as wheat and barley.

Accordingly in a still further aspect the invention provides a process for regulating the growth of a plant which process comprises applying to the plant, to the seed of the plant, or to the growth medium of the plant, an effective amount of a compound of formula I, as hereinbefore defined.

To effect the plant growth regulating process of the present invention the compounds of formula I may be applied directly to the plant (post-emergence application) or to the seed or soil before the emergence of the plant (pre-emergence) application.

The compounds of formula I may be used on their own to regulate the growth of plants but in general are preferably used in the form of a composition comprising a compound of the invention in admixture with a carrier comprising a solid or liquid diluent. Therefore, in a still further aspect the invention provides plant growth regulating compositions comprising a compound of formula I as hereinbefore defined and an agriculturally acceptable carrier therefor.

The compositions of the present invention may be in the form of solids, liquids or pastes. The compositions include both dilute compositions which are ready for immediate use and concentrated compositions which may require dilution before use. Therefore, the concentration of the active ingredient in the compositions of the present invention will vary depending on the types of formulation and whether the composition is ready for use such as, for example, a dust formulation or an aqueous emulsion or whether the composition is a concentrate such as, for example, an emulsifiable concentrate or a wettable powder, which is suitable for dilution before use. Therefore, the concentration of the active ingredient in the compositions of the present invention will vary depending on the types of formulation and whether the composition is ready for use such as, for example, a dust formulation or an aqueous emulsion or whether the composition is a concentrate such as, for example, an emulsifiable concentrate or a wettable powder, which is suitable for dilution before use. In general the compositions of the present invention comprise from 1 ppm to 99% by weight of active ingredient.

The solid compositions may be in the form of powders, dusts, pellets, grains, and granules wherein the active ingredient is mixed with a solid diluent. powders and dusts may be prepared by mixing or grinding the active ingredient with a solid carrier to give a finely divided composition. Granules, grains and pellets may be prepared by bonding the active ingredient to a solid carrier, for example, by coating or impregnating the preformed granular solid carrier with the active ingredient or by agglomeration techniques.

Examples of solid carriers include: mineral earths and clays such as, for example, kaolin, bentonite, kieselguhr, Fuller's earth, Attaclay, diatomaceous earth, bole, loess, talc, chalk, dolomite, limestone, lime, calcium carbonate, gypsum, calcium sulfate, pyrophyllite, silicic acid, silicates and silica gels; fertilizers such as, for example, ammonium sulfate, ammonium phosphate, ammonium nitrate and urea; natural products of vegetable origin such as, for example, grain meals and flours, bark meals, wood meals, nutshell meals and cellulosic powders; and synthetic polymeric materials such as, for example, ground or powdered plastics and resins.

Alternatively, the solid compositions may be in the form of dispersible or wettable dusts, powders, granules or grains wherein the active ingredient and the solid carrier are combined with one or more surface active agents which act as wetting, emulsifying and/or dispersing agents to facilitate the dispersion of the active ingredient in liquid.

Examples of surface active agents include those of the cationic, anionic and non-ionic type. Cationic surface active agents include quaternary ammonium compounds, for example, the long chain alkylammonium salts such as cetyltrimethylammonium bromide. Anionic surface active agents include: soaps or the alkali metal, alkaline earth metal and ammonium salts of fatty acids; the alkali metal, alkaline earth metal and ammonium salts of ligninsulfonic acid; the alkali metal, alkaline earth metal and ammonium salts of arylsulfonic acids including the salts of naphthalenesulfonic acids such as butylnaphthalenesulfonic acids, the di- and tri- isopropylnaphthalenesulfonic acids, the salts of the condensation products of sulfonated naphthalene and naphthalene derivatives with formaldehyde, the salts of the condensation products of sulfonated naphthalene and naphthalene derivatives with phenol and formaldehyde, and the salts of alkylarylbenzenesulfonic acids such as dodecylbenzenesulfonic acid; the alkali metal, alkaline earth metal and ammonium salts of the long chain mono esters of sulfuric acid or alkylsulfates such as laurylsulfate and the mono esters of sulfuric acid with fatty alcohol glycol ethers. Nonionic surface active agents include: the condensation products of ethylene oxide with phenols and alkylphenols such as isooctylphenol, octylphenol and nonylphenol; the condensation products of ethylene oxide with castor oil; the partial esters derived from long chain fatty acids and hexitol anhydrides, for example sorbitan monolaurate, and their condensation products with ethylene oxide; ethylene oxide/propylene oxide block copolymers; lauryl alcohol polyglycol ether acetal; and the lecithins.

The liquid compositions may comprise a solution or dispersions of the active ingredient in a liquid carrier optionally containing one or more surface active agents which act as wetting, emulsifying and/or dispersing agents. Examples of liquid carriers include: water; mineral oil fractions such as, for example, kerosene, solvent naphtha, petroleum, coal tar oils and aromatic petroleum fractions; aliphatic, cycloaliphatic and aromatic hydrocarbons such as, for example, paraffin, cyclohexane, toluene, the xylenes, tetrahydronaphthalene and alkylated naphthalenes; alcohols such as, for example, methanol, ethanol, propanol, isopropanol, butanol, cyclohexanol and propylene glycol; ketones such as, for example, cyclohexanone and isophorone; and strongly polar organic solvents such as, for example, dimethylformamide, dimethylsulfoxide, N-methylpyrrolidone and sulfolane.

A preferred liquid composition comprises an aqueous suspension, dispersion or emulsion of the active ingredient which is suitable for application by spraying, atomizing or watering. Such aqueous compositions are generally prepared by mixing concentrated compositions with water. Suitable concentrated compositions include emulsion concentrates, pastes, oil dispersions, aqueous suspensions and wettable powders. The concentrates are usually required to withstand storage for prolonged periods and after such storage to be capable of dilution with water to form aqueous preparations which remain homogeneous for a sufficient time to enable them to be applied by conventional spray equipment. The concentrates conveniently contain from 20 to 99%, preferably 20 to 60%, by weight of active ingredient.

Emulsion or emulsifiable concentrates are conveniently prepared by dissolving the active ingredient in an organic solvent containing one or more surface active agents and optionally an oil. Oil dispersions may be prepared by grinding together the active ingredient, a hydrocarbon oil, and one or more surface active agents. Aqueous suspension concentrates may conveniently be prepared by ball milling a mixture of the active agent and preferably at least one suspending agent. Suitable suspending agents include: hydrophilic colloids such as, for example, poly(N-vinylpyrrolidone), sodium carboxymethylcellulose and the vegetable gums, gum acacia and gum tragacanth; hydrated colloidal mineral silicates such as, for example, montmorillonite, beidellite, nontronite, hectorite, saponite, sauconite and bentonite; other cellulose derivatives; and poly(vinyl alcohol). Wettable powder concentrates may conveniently be prepared by blending together the active ingredient, one or more surface active agents, one or more solid carriers and optionally one or more suspending agents and grinding the mixture to give a powder having the required particle size.

The aqueous suspensions, dispersions or emulsions may be prepared from the concentrated compositions by mixing the concentrated compositions with water optionally containing surface active agents and/or oils.

It should be noted that the compounds of the invention of formula I wherein R¹ is hydrogen are acidic. Therefore, the compounds of formula I may be formulated and applied as the salts of organic or inorganic bases. In formulating and employing the compounds of formula I in the form of their salts either either the salts per se, that is the compounds of formula I wherein R¹ is an inorganic or an organic cation, may be used in the formulation or the compounds of formula I wherein R¹ is hydrogen may be used in the formulation and the salts generated in situ by the use of the appropriate organic or inorganic base.

The mode of application of the compositions of the invention will depend to a large extent on the type of composition used and the facilities available for its application. Solid compositions may be applied by dusting or any other suitable means for broadcasting or spreading the solid. Liquid compositions may be applied by spraying, atomizing, watering, introduction into the irrigation water, or any other suitable means for broadcasting or spreading the liquid.

The rate of application of the compounds of the invention will depend on a number of factors including, for example, the compound chosen for use, the identity of the plants whose growth is to be inhibited the formulations selected for use and whether the compound is to be applied for foliage or root uptake. As a general guide, however, an application rate of from 0.005 to 20 kilograms per hectate is suitable while from 0.01 to 5.0 kilograms per hectare may be preferred.

The compositions of the invention may comprise, in addition to one or more compounds of the invention, one or more compounds not of the invention but which possess biological activity. For example, as hereinbefore indicated the compounds of the invention are in general substantially more effective against monocotyledonous plants or grass species than against dicotyledonous plants or broad-leaved species. As a result, in certain applications the herbicidal use of the compounds of the invention alone may not be sufficient to protect a crop. Accordingly in yet a still further embodiment the invention provides a herbicidal composition comprising a mixture of at least one herbicidal compound of formula I as hereinbefore defined with at least one other herbicide.

The other herbicide may be any herbicide not having the formula I. It will generally be a herbicide having a complementary action. For example, one preferred class is of mixtures comprising a herbicide active against broad-leaved weeds. A second preferred class is of mixtures comprising a contact herbicide.

Example of useful complementary herbicides include:

A. benzo-2,1,3,-thiadiazin-4-one-2,2-dioxides such as 3-isopropylbenzo-2,1,3-thiadiazin-4-one-2,2-dioxide (common name bentazon);

B. hormone herbicides and in particular the phenoxyalkanoic acids such as 4-chloro-2-methylphenoxy acetic acid (common name MCPA), 2-(2,4-dichlorophenoxy)propionic acid (common name dichlorprop), 2,4,5-trichlorophenoxyacetic acid (common name 2,4,5-T), 4-(4-chloro-2-methylphenoxy)butyric acid (common name 2,4-D), 4-(2,4-dichlorophenoxy)butyric acid (common name 2,4-DB), 2-(4-chloro-2-methylphenoxy)propionic acid (common name mecoprop), and their derivatives (eg salts, esters, amides and the like);

C. 3-[4-(4-halophenoxy)phenyl]-1,1-dialkylureas such as 3-[4-(4-chlorophenoxy)phenyl]-1,1-dimethylurea (common name chloroxuron);

D. dinitrophenols and their derivatives (eg acetates) such as 2-methyl-4,6-dinitrophenol (common name DNOC), 2-tertiarybutyl-4,6-dintrophenol (common name dinoterb), 2-secondarybutyl-4,6-dinitrophenol (common name dinoseb) and its ester dinoseb acetate;

E. dinitroaniline herbicides such as N',N'-diethyl-2,6-dinitro-4-trifluoromethyl-m-phenylenediamine (common name dinitramine), 2,6-dinitro-N,N-dipropyl-4-trifluoromethylaniline (common name trifluralin) and 4-methylsulfonyl-2,6-dinitro-N,N-dipropylaniline (common name nitralin);

F. phenylurea herbicides such as N'-(3,4-dichlorophenyl)-N,N-dimethylurea (common name diruon) and N,N-dimethyl-N'-[3-(trifluoromethyl)phenyl]urea (common name fluometuron);

G. phenylcarbamoyloxyphenylcarbamates such as 3[(methoxycarbonyl)amino]phenyl (3-methylphenyl)carbamate (common name phenmedipham) and 3-[(ethoxycarbonylamino]phenyl phenylcarbamate (common name desmedipham);

H. 2-phenylpyridazin-3-ones such as 5-amino-4-chloro-2-phenylpyridazin-3-one (common name pyrazon);

I. uracil herbicides such as 3-cyclohexyl-5,6-trimethyleneuracil (common name lenacil), 5-bromo-3-sec-butyl-6-methyluracil (common name bromacil) and 3-tert-butyl-5-chloro-6-methyluracil (common name terbacil);

J. triazine herbicides such as 2-chloro-4-ethylamino-6-(iso-propylamino)-1,3,5-triazine (common name atrazine). 2-chloro-4,6-di(ethylamino)-1,3,5-triazine (common name simazine) and 2-azido-4-iso-propylamino)-6-methylthio-1,3,5-triazine (common name aziproptryne);

K. 1-alkoxy-2-alkyl-3-phenylurea herbicides such as 3-(3,4-dichlorophenyl)-1-methoxy-1-methylurea (common name linuron), 3-(4-chlorophenyl)-1-methoxy-1-methylurea (common name monolinuron) and 3-(4-bromo-4-chlorophenyl)-1-methoxy-1-methylurea (common name chlorobromuron);

L. thiolcarbamate herbicides such as S-propyl dipropylthiocarbamate (common name verolate);

M. 1,2,4-triazin-5-one herbicides such as 4-amino-4,5-dihydro-3-methyl-6-phenyl-1,2,4-triazine-5-one (common name metamitron) and 4-amino-6-tert-butyl 4,5-dihydro-3-methylthio-1,3,4-triazin-5-one (common name metribuzin);

N. benzoic acid herbicides such as 2,3,6-trichlorobenzoic acid (common name 2,3,6-TBA), 3,6-dichloro2-methoxybenzoic acid (common name dicamba) and 3-amino-2,5-dichlorobenzoic acid (common name chloramben);

O. anilide herbicides such as N-butoxymethyl-α-chloro-2',6'-diethylacetanilide (common name butachlor), the corresponding N-methoxy compound (common name alachlor), the corresponding N-isopropyl compound (common name propachlor) and 3',4'-dichloropropionanilide (common name propanil);

P. dihalobenzonitrile herbicides such as 2,6-dichlorobenzonitrile (common name dichlobenil), 3,5-dibromo-4-hydroxybenzonitrile (common name bromoxynil) and 3,5-diiodo-4-hydroxybenzonitrile (common name ioxynil);

Q. haloalkanoic herbicides such as 2,2-dichloropropionic acid (common name dalapon), trichloroacetic acid (common name TCA) and salts thereof;

R. diphenylether herbicides such as 4-nitrophenyl 2-nitro-4-trifluoromethylphenyl ether (common name fluorodifen), methyl 5-(2,4-dichlorophenoxy)-2-nitrobenzoate (common name bifenox), 2-nitro-5-(2-chloro-4-trifluoromethylphenoxy)benzoic acid and 2-chloro-4-trifluoromethylphenyl 3-ethoxy-4-nitrophenyl ether;

S. N-(heteroarylaminocarbonyl)benzenesulfonamides such as 2-chloro-N-[(4-methoxy-6-methyl-1,3,5-triazin-2-yl)aminocarbonyl]benzenesulfonamide (commonly known as DPX 4189); and

T. miscellaneous herbicides including N,N-dimethyldiphenylacetamide (common name diphenamid), N-(1-naphthyl)phthalamic acid (common name naptalam) and 3-amino-1,2,4-triazole.

Examples of useful contact herbicides include:

U. bipyridylium herbicides such as those in which the active entity is the 1,1'-dimethyl-4,4'-dipyridylium ion (common name paraquat) and those in which the active entity is the 1,1'-ethylene-2,2'-dipyridylium ion (common name diquat);

V. organoarsenical herbicides such as monosodium methanearsonate (common name MSMA); and

W. amino acid herbicides such as N-(phosphonomethyl)-glycine (common name glyphosate) and its salts and esters.

The invention is now illustrated by but in no way limited to the following Examples.

EXAMPLE 1

This example details the preparation of precursors to carboxaldehydes of formula V which were used in the preparation of compounds of the invention of formula I.

(a) 3-Chloro-4-cyano-1-methyl-5,6,7,8-tetrahydroisoquinoline was prepared following essentially the same procedure as that described in J. Org. Chem, 1968, 33, 3648 and was obtained as white crystals, mp 98° C.

(b) 4-Cyano-3-methoxy-1-methyl-5,6,7,8-tetrahydroisoquinoline.

3-Chloro-4-cyano-1-methyl-5,6,7,8-tetrahydroisoquinoline (10.0 g) was refluxed with sodium methoxide (1.1 equiv) in a mixture of methanol (150 ml) and anhydrous dimethylformamide (20 ml) for 24 hr. The bulk of the solvent was evaporated under reduced pressure, water was added to the residue and the resulting mixture was extracted with ether. The dried (MgSO₄) organic fraction was evaporated and the residue was purified by column chromatography over silica gel with dichloromethane elution to give 4-cyano-3-methoxy-1-methyl-5,6,7,8-tetrahydroisoquinoline as white crystals, mp 116° C. Pmr spectrum (CDCl₃ ; δ in ppm): 1.81 (4H,m); 2.39 (3H,s); 2.50-2.94 (4H,m); 3.98 (3H, s).

(c) 4-Cyano-3-methoxy-1-methyl-5,6,7,8-tetrahydroisoquinolin-8-one was prepared from 4-cyano-3-methoxy-1-methyl-5,6,7,8-tetrahydroisoquinoline following essentially the same procedure as that described in Tetrahedron, 1975, 31, 527 for the synthesis of 4-cyano-3-ethoxy-1-methyl-5,6,7,8-tetrahydroisoquinolin-8-one and was obtained as white crystals, mp 128° C. Pmr spectrum (CDCl₃ ; δ in ppm): 2.04-3.19 (6H,m); 2.86 (3H,s); 4.12 (3H,s).

(d) 8-Bromo-5,6,7-trimethylquinoline

(i) 3,4,5-Trimethylacetanilide was prepared following essentially the same procedure as J. Amer. chem. Soc., 1953, 75, 2635 and was obtained as white crystals, mp 169° C.

(ii) A solution of bromine (5.6 g) in glacial acetic acid (8.5 ml) was added dropwise to a stirred suspension of 3,4,5-trimethylacetanilide (6.0 g) in glacial acetic acid (50 ml). After stirring at room temperature for 3 hr, the mixture was poured into water (200 ml). The solid was filtered off, washed with water and dried in air to give 2-bromo3,4,5-trimethylacetanilide as a light brown powder, mp 156° C.

(iii) Concentrated hydrochloric acid (10 ml) was added dropwise to a suspension of 2-bromo3,4,5-trimethylacetanilide (8.0 g) in refluxing ethanol (45 ml). After 1 hr water (100 ml) was added to the mixture. The bulk of the solvent was evaporated under reduced pressure and the residue was stirred with water (100 ml). The mixture was made basic by addition of 10% aqueous sodium hydroxide and the solid was filtered off, washed with water and dried in air to give 2-bromo-3,4,5-trimethylaniline as a light brown powder, mp 69° C.

(iv) 2-Bromo-3,4,5-trimethylaniline (10.4 g), glycerol (4 equiv) and arsenic oxide (0.75 equiv) were stirred and heated to 100° C. Concentrated sulfuric acid (60% w/w of the glycerol) was added to the mixture dropwise. After heating at 130° C. for 4 hr, the cooled mixture was diluted with water and neutralised with aqueous ammonia. The solid was filtered off, washed with water and dried in air. Purification by column chromatography over alumina with dichloromethane elution gave 8-bromo-5,6,7-trimethylquinoline as a white solid, mp 180° C. Pmr spectrum (CDCl₃ ; δ in ppm): 2.50 (3H,s); 2.61 (3H,s); 2.74 (3H,s); 7.37-8.98 (3H,m).

(e) 2-Methoxy-4-methylnaphthalene

(i) 7-Methoxy-5-methyl-1,2,3,4-tetrahydronaphthalen-1-one was prepared from m-cresyl methyl ether following essentially the same procedure as that described in Aust. J. Chem., 1978, 31, 1363. Purification of the crude product by column chromatography over silica with dichloromethane elution gave a pale yellow solid, mp 55° C.

(ii) 7-Methoxy-5-methyl-1,2,3,4-tetrahydronaphthalene was prepared from 7-methoxy-5-methyl-1,2,3,4-tetrahydronaphthalen-1-one following essentially the same procedure as that described in J. Amer. Chem. Soc., 1953, 75, 3162 and was obtained as a colourless oil.

(iii) A mixture of 7-methoxy-5-methyl-1,2,3,4-tetrahydronaphthalene (1.0 g) and 10% palladium on charcoal (1.0 g) was stirred and heated in diphenyl ether (2 ml) at 200° C. for 1 hr. The mixture was purified by column chromatography over silica with light petroleum/dichloromethane (1:1 v/v) elution to give 2-methoxy-4-methylnaphthalene as a low melting point solid. Pmr spectrum (CDCl₃ ; δ in ppm): 2.64 (3H,s); 3.89 (3H,s); 7.0-7.9 (6H,m).

(v) 1-Methylnaphthalene, 2-methylnaphthalene, 1,3-dimethylnaphthalene, 1,4-dimethylnaphthalene, 2,3-dimethylnaphthalene, 2,6-dimethylnaphthalene, 4-methylquinoline, 6-methylquinoline and 2,6-dimethylquinoline were commercially available products.

EXAMPLE 2

This example details the preparation of carboxaldehydes of formula V which were used in the preparation of compounds of the invention of formula I.

(a) 3-Chloro-1-methyl-5,6,7,8-tetrahydroisoquinoline-4-carboxaldehyde was prepared from 3-chloro-4-cyano-methyl-5,6,7,8-tetrahydroisoquinoline by reduction with diisobutylaluminium hydride following essentially the same procedure as that described in J. Org. chem., 1980, 45, 1354 for the reduction of 3-cyano-2-methoxy-6-methylpyridine. Pmr spectrum (CDCl₃ ; δ in ppm): 1.79 (4H,m); 2.47 (3H,s); 2.59-3.18 (4H,m); 10.52 (1H,s).

(b) 6-Methylquinoline-2-carboxaldehyde and quinoline-4-carboxaldehyde were prepared from 2,6-dimethylquinoline and 4-methylquinoline respectively by selenium dioxide oxidation following essentially the same procedures as those described in Organic Reactions, vol 24, ch. 4. Quinoline-6-carboxaldehyde was similarly prepared from 6-methylquinoline following essentially the same procedure as that described in J. Gen. chem. USSR, 1944, 14, 330 (Chem. Abstr., 1945, 39, 40772)

(c) 2-Methylnaphthalene-1-carboxaldehyde, 2,3-dimethylnaphthalene-1-carboxaldehyde, 2,4-dimethylnaphthalene-1-carboxaldehyde, 3,4-dimethylnaphthalene-1-carboxaldehyde, 2,3,4-trimethylnaphthalene-1-carboxaldehyde, 1,4-dimethylnaphthalene-2-carboxaldehyde and 1,3,4,-trimethylnaphthalene-2-carboxaldehyde were prepared from the appropriate methyl-substituted naphthalene by reaction with dichloromethyl methyl ether and titanium (IV) chloride as catalyst following essentially the same procedure as that described in J. Chem. Soc. Perkin I, 1972, 892. 4-Methylnaphthalene-1-carboxaldehyde and 2-methoxy-4-methylnaphthalene-1-carboxaldehyde were similarly prepared from 1-methylnaphthalene and 2-methoxy-4-methylnaphthalene respectively.

(d) 2-Bromo-4-methylnaphthalene-1-carboxaldehyde. n-Butyl lithium (1.1 ml; 1.55M in hexane) was added to a solution of N-methylpiperazine (0.35 g) in anhydrous toluene (8 ml) at 0° C. The solution was warmed to room temperature and 4-methylnaphthalene-1-carboxaldehyde (0.51 g; 3 mmol) was added dropwise. After 15 min n-butyl lithium (9 mmol) was added dropwise with stirring. The mixture was heated at 80° C. for 12 hr under a nitrogen atmosphere. After cooling to room temperature, anhydrous tetrahydrofuran (8 ml) was added and the mixture was cooled to -42° C. Bromine (18 mmol) was added to the mixture dropwise and the solution was then warmed to room temperature. Ether (50 ml) was added and the mixture was washed successively with water, aqueous sodium bisulfite and water. The dried (MgSO₄) organic fraction was evaporated and the residue was purified by column chromatography over silica gel with dichloromethane/light petroleum (1:2 v/v) elution to give 2-bromo-4-methylnaphthalene-1-carboxaldehyde (0.4 g) as a light yellow solid, mp 93° C. Pmr spectrum (CDCl₃ ; δ in ppm): 2.14 (3H,s); 7.45-9.07 (5H,m); 10.62 (1H,s).

(e) 3-Methylnaphthalene-2-carboxaldehyde and 6-methylnaphthalene-2-carboxaldehyde.

2,3-Dimethylnaphthalene (20.0 g), N-bromosuccinimide (22.8 g) and benzoyl peroxide (0.2 g) were refluxed in carbon tetrachloride (160 ml) for 12 hr. After cooling, the mixture was filtered. The filtrate was evaporated under reduced pressure and the residue was dissolved in chloroform. This solution was added dropwise to a vigorously stirred solution of hexamethylenetetramine (1.2 equiv) in chloroform (100 ml) and the mixture was heated at reflux for 12 hr. After cooling the salt was filtered off and was washed with several portions of hexane. The dried salt was heated at reflux with a 50% aqueous acetic acid solution (20 ml/g) for 2 hr. Concentrated hydrochloric acid (2 ml/g) was added and the mixture was heated at reflux for a further 15 min. The solution was poured onto ice-water and the resulting mixture was extracted with ether. The dried (MgSO₄) organic fraction was evaporated and the residue was purified by recrystallization (twice) from hexane to give 3-methylnaphthalene-2-carboxaldehyde as cream-coloured clusters, mp 119° C. Pmr spectrum (CDCl₃ ; δ in ppm): 2.75 (3H,s); 7.32-7.98 (5H,m); 8.24 (1H,s); 10.27 (1H,s). 6-Methylnaphthalene-2-carboxaldehyde was similarly prepared from 2,6-dimethylnaphthalene and was obtained as a white solid, mp 120° C. Pmr spectrum (CDCl_(3;) δ in ppm): 2.58 (3H,s); 7.38-8.07 (5H,m); 8.30 (1H,s); 10.14 (1H,s).

(f) 5,6,7-Trimethylquinoline-8-carboxaldehyde n-Butyl lithium (2.1 equiv; 1.55M in hexane) was added slowly to a suspension of 8-bromo-5,6,7-trimethylquinoline (4.2 g) in anhydrous THF (40 ml) under nitrogen at -90° C. After 3 hr a solution of N-formylpiperidine (2.1 equiv) in anhydrous THF (10 ml) was added and the mixture was warmed to -40° C. over ca. 2 hr. A dilute sulfuric acid solution (1N; 20 ml) was added and the mixture was warmed to room temperature. The mixture was made basic by the addition of potassium carbonate and was then extracted with ether. The dried (MgSO₄) organic fraction was evaporated and the residue was purified by column chromatography over alumina with carbon tetrachloride/dichloromethane (1:1 v/v) elution to give 5,6,7-trimethylquinoline-8-carboxaldehyde as a pale yellow solid, mp 162° C. Pmr spectrum (CDCl₃ ; δ in ppm): 2.48 (3H,s); 2.68 (3H,s); 2.74 (3H,s); 7.43-8.96 (3H,m); 11.61 (1H,s).

EXAMPLE 3

The 1-(aryl or heteroaryl)but-1-en-3-one derivatives of formula VI used in the preparation of compounds of the formula I were prepared from the appropriate carboxaldehydes of formula V by one of the following methods:

(a) 3-Chloro-1-methyl-5,6,7,8-tetrahydroisoquinoline-4-carboxaldehyde (4.0 g) was stirred with a few drops of a 2% aqueous sodium hydroxide solution in aqueous acetone (1:2 v/v; 20 ml) at room temperature for 4 hr. The mixture was poured into water which was then extracted with diethyl ether. The residue obtained after evaporation of the dried (MgSO₄) organic extract was purified by column chromatography over silica with dichloromethane elution to give 1-(3-chloro-1-methyl-5,6,7,8-tetrahydroisoquinolin-4-yl)-but-1-en-3-one as white crystals, mp 90° C.

(b) A mixture of quinoline-6-carboxaldehyde (5.29 g) and 1-triphenylphosphoranylidene-2-propanone (1.5 equiv) in dimethyl sulfoxide (100 ml) was stirred at room temperature for 24 hr. The solution was poured into water (600 ml) which was subsequently extracted with ethyl acetate. The dried (MgSO₄) organic fraction was evaporated under reduced pressure and the residue was purified by column chromatography over silica with dichloromethane/ethyl acetate (4:1 v/v) elution to give 1-(quinolin-6-yl)but-1-ene-3-one as a white solid. Pmr spectrum (CDCl₃ ; δ in ppm : 2.41 (3H,s); 6.83 (1H,d); 7.3-9.0 (7H,m).

(c) 1-(3-Methoxy-1-methyl-5,6,7,8-tetrahydroisoquinolin-4-yl)but-1-en-3-one. Reduction of 4-cyano-3-methoxy-1-methyl-5,6,7,8-tetrahydroisoquinoline following essentially the same procedure as that described in Example 2 part (a) gave a mixture of the starting material and 3-methoxy-1-methyl-5,6,7,8-tetrahydroisoquinoline-4-carboxaldehyde. Reaction of the mixture with acetone following essentially the same procedure as that described in Example 3 method (a) gave, after purification by column chromatography over silica with dichloromethane elution, 1-(3-methoxy-1-methyl-5,6,7,8-tetrahydroisoquinolin-4-yl)but-1-en-3-one as a white solid, mp 76° C.

(d) 1-(8-Hydroxy-3-methoxy-1-methyl-5,6,7,8-tetrahydroisoquinolin-4-yl)but-1-en-3-one.

Diisobutylaluminium hydride (4 equiv; 25% solution in toluene) was added dropwise under nitrogen to a solution of 4-cyano-3-methoxy-1-methyl-5,6,7,8-tetrahydroisoquinolin-8-one (6.0 g) in anhydrous toluene (40 ml) at 0° C. After stirring for 1.5 hr a saturated aqueous ammonium chloride solution (20 ml) was carefully added dropwise and the mixture was stirred for a further 15 min at 0° C. The mixture was extracted with ethyl acetate and the dried (MgSO₄) organic fraction was evaporated under reduced pressure to give 8-hydroxy-3-methoxy-1-methyl-5,6,7,8-tetrahydroisoquinoline-4-carboxaldehyde. Reaction of the crude aldehyde with acetone following essentially the same procedure as that described in Example 3 method (a) gave, after purification by column chromatography over silica with dichloromethane/ethyl acetate (1:1 v/v) elution; 1-(8-hydroxy-3-methoxy-1-methyl-5,6,7,8-tetrahydroisoquinolin-4-yl)but-1-en-3-one as a white solid, mp 107° C. Pmr spectrum (CDCl₃ ; δ in ppm): 1.66-3.16 (7H,m); 2.35 (3H,s); 2.61 (3H, s); 4.02 (3H,s); 4.94 (1H,brs); 6.94 (1H,d); 7.69 (1H,d).

The specific method used for the preparation of each 1-(aryl or heteroaryl)but-1-en-3-one is indicated in Table 3, Example 6.

EXAMPLE 4

The 2-acyl-5-(aryl or heteroaryl)-3-hydroxycyclohex-2-en-1-one derivatives of formula XIII used in the preparation of compounds of the formula I were prepared from the appropriate compounds of formula VI by one of the following methods:

(a) 1-(3-Chloro-1-methyl-5,6,7,8-tetrahydroisoquinolin-4-yl)but-1-en-3-one (3.2 g) was heated at reflux with sodium diethyl malonate (1.1 equiv) in dry absolute ethanol (50 ml) for 3 hr. The solvent was evaporated and the residue was thoroughly dried (100° C.; <0.1 mmHg). Dry dimethylformamide (30 ml) was added and the mixture was heated to 60° C. under nitrogen. n-Butyric anhydride (1.1 equiv) was added and the mixture was heated at 100° C. for 20 min. The solvent was evaporated under reduced pressure and the residue was heated at reflux with an aqueous potassium hydroxide solution (2 equiv; 30 ml) for 4 hr. After cooling, the mixture was extracted with diethyl ether. The aqueous layer was recovered and was heated to ca 80° C. The solution was acidified (to pH 5) by dropwise addition of a dilute hydrochloric acid solution. After cooling, the mixture was extracted with diethyl ether. The residue obtained after evaporation of the dried (MgSO₄) organic extract was purified by column chromatography over silica gel with dichloromethane/ethyl acetate (9:1 v/v) elution to give 2-butyryl-5-(3-chloro-1-methyl-5,6,7,8-tetrahydroisoquinolin-4-yl)-3-hydroxycyclohex-2-en-1-one as a pale yellow oil.

(b)

(i) Diethyl malonate (9.82 g) was added to a solution of sodium metal (1.41 g) in anhdrous absolute ethanol (50 ml). 1-(2,3-Dimethylnaphth-1-yl)but-1-en-3-one (12.5 g) was added to the solution and the mixture was heated under reflux for 2 hr. A slight excess of an aqueous solution of potassium hydroxide was added and the mixture was heated under reflux for a further 5 hr. The hot mixture was acidified by dropwise addition of a dilute aqueous hydrochloric acid solution. After cooling, the product was filtered off and washed with a little diethyl ether to give 3-hydroxy-5-(2,3-dimethylnaphth-1-yl)-cyclohex-2-en-1-one as a white solid, mp 242° C.

(ii) A mixture of 3-hydroxy-5-(2,3-dimethylnaphth-1-yl)cyclohex-2-en-1-one (1.5 g), butyric anhydride (4 ml) and butyric acid (4 ml) was stirred and heated at 110° C. until homogeneous. Trifluoromethanesulfonic acid (5 drops) was added and the mixture was heated at 110°-120° C. for 1 hour under an atmosphere of nitrogen. The mixture was poured with stirring into ice-water, neutralized with sodium bicarbonate and then extracted with diethyl ether. The dried (MgSO₄) organic extract was evaporated and the residue was purified by column chromatography over silica gel with dichloromethane elution to give 3-hydroxy-5-(2,3-dimethylnaphth-1-yl)-2-butyrylcyclohex-2-en-1-one as a pale yellow oil.

(c)

(i) 3-Hydroxy-5-(naphth-1-yl)cyclohex-2-en-1-one was prepared from 1-(naphth-1-yl)but-1-en-3-one following essentially the same procedure as that described in Example 4, method (b), part (i) and was obtained as a white solid.

(ii) Stannic chloride (12.0 g) was added dropwise to a mixture of 3-hydroxy-5-(naphth-1-yl)-cyclohex-2-en-1-one (10 g) and propionyl chloride (4.25 g) in 1,2-dichloroethane (50 ml). the mixture was stirred and heated at reflux under nitrogen for 6 hr. After cooling, the mixture was poured onto ice. The dichloromethane extract was evaporated and the residue was heated at reflux with a 2M sodium hydroxide solution (20 ml) for 2 hr. After cooling, the solution was poured into an ice/hydrochloric acid mixture. The dried (Na₂ SO₄) dichloromethane extract was concentrated and the residue was purified by column chromatography over silica gel with dichloromethane elution to give 3-hydroxy-5-(naphth-1-yl)-2-propionylcyclohex-2-en-1-one as a white solid.

(d)

(i) 3-Hydroxy-5-(naphth-2-yl)cyclohex-2-en-1-one was prepared from 1-(naphth-2-yl)but-1-en-3-one following essentially the same procedure as that described in Example 4, method (b), part (i) and was obtained as a white solid.

(ii) Propionic anhydride (25 ml) was added cautiously to freshly prepared sodium methoxide (0.1 g). 3-Hydroxy-5-(naphth-2-yl)-cyclohex-2-en-1-one (4.35 g) was added and the reaction mixture was heated at 160°-180° C. for a period of 2 hrs. The excess propionic anhydride was removed by distillation under reduced pressure. Aqueous 20% sodium hydroxide solution (50 ml) was added to the residue and the mixture was heated at reflux for 2 hrs with vigorous stirring. After cooling, the mixture was poured onto ice/hydrochloric acid. The dried (Na₂ SO₄) dichloromethane extract ws concentrated and the residue was purified by column chromatography over silica gel with dichloromethane elution to give 3-hydroxy-5-(naphth-2-yl)-2-propionylcyclohex-2-en-1-one as a pale yellow solid, mp 125° C.

(e)

(i) 3-Hydroxy-5-(3-methylnaphth-2-yl)cyclohex-2-1-one was prepared from 1-(3-methyl-naphth-2-yl)but-1-en-3-one following essentially the same procedure as that described in Example 4, method (b), part (i) and was obtained as a white solid, mp 210° C.

(ii) 3-Hydroxy-5-(3-methylnaphth-2-yl)cyclohex-2-en-1-one (1.2 g) was added to a suspension of sodium hydride (0.126 g) in anhydrous dimethylformamide (15 ml). The mixture was stirred and heated at 60° C. under nitrogen. After 10 minutes, propionic anhydride (0.69 ml) was added and the mixture was heated at 110° C. for 30 min. After cooling, the mixture was poured onto ice/hydrochloric acid. The dried (MgSO₄) diethyl ether extract was evaporated and the residue was purified by column chromatography over silica gel with chloroform elution to give 3-hydroxy-5-(3-methylnaphth-2-yl)-2-propionylcyclohex-2-en-1-one as a pale yellow solid, mp 118° C.

(f)

(i) 3-Hydroxy-5-(quinolin-4-yl)cyclohex-2-en-1-en-3-one following essentially the same procedure as that described in Example 4, method (b), part (i) and was obtained as a brown solid, mp 190°-195° C.

(ii) To a solution of 3-hydroxy-5-(quinolin-4-yl)-cyclohex-2-en-1-one (80 mg) in pyridine (250 mg) and chloroform (2 ml) was added, with shaking, propionyl chloride (300 mg). The mixture was stirred briefly at room temperature, diluted with chloroform (15 ml), washed with water (10 ml) and was then dried over anhydrous magnesium sulfate. Evaporation of the solvent gave the intermediate O-propionyl derivative which was dissolved in toluene (15 ml). The solution was heated to boiling and 4-dimethylaminopyridine (100 mg) was added. The mixture was heated at reflux for 2.5 hr, cooled and was washed with water. The dried (MgSO₄) organic fraction was evaporated and the residue was purified by column chromatography over silica with chloroform elution to give 3-hydroxy-2-propionyl-5-(quinolin-4-yl)cyclohex-2-en-1-one as a colourless solid.

(g) 2-Butyryl-5-[4-(N,N-dimethylsulfonamido)naphth-1-yl]-3-hydroxycyclohex-2-en-1-one

(i) Chlorosulfonic acid (3.0 g) was added dropwise to a solution of 2-butyryl-3-hydroxy-5-(naphth-1-yl)cyclohex-2-en-1-one (1.3 g) in chloroform (15 ml) at 0° C. The mixture was stirred at 0° C. for 1 hr and at room temperature for 18 hrs. The mixture was poured onto ice-water (200 ml) which was subsequently extracted with dichloromethane. The dried (Na₂ SO₄) organic extract was evaporated to give 2-butyryl-5-(4-chlorosulfonylnaphth-1-yl)-3-hydroxy cyclohex-2-en-1-one as a brown foam. Pmr spectrum (CDCl₃ ; δ in ppm): 1.03 (3H,t); 1.43-1.89 (2H,m); 2.69-3.26 (6H,m); 4.00-4.49 (1H,m); 7.32-8.97 (6H,m); 18.35 (1H,s).

(ii) 2-Butyryl-5-(4-chlorosulfonylnaphth-1-yl)-3-hydroxycyclohex-2-en-1-one (0.82 g) was added in portions over 15 min to a well-stirred mixture of dimethylamine (33% in ethanol; 10 ml) and ethanol (30 ml) at 0° C. After 1 hr at 0° C. and 18 hrs at room temperature the mixture was acidified (to pH 3) by addition concentrated hydrochloric acid. The mixture was concentrated by evaporation of the solvent under reduced pressure and the residue was partitioned between ethyl acetate (100 ml) and water (100 ml). The dried (Na₂ SO₄) organic fraction was evaporated and the residue was purified by column chromatography over silica with 1% methanolic dichloromethane elution to give 2-butyryl-5-[4-(N,N-dimethylsulfonamido)naphth-1-yl]-3-hydroxycyclohex-2-en-1-one (0.20 g) as a yellow oil. Pmr spectrum (CDCl₃ ; δ in ppm): 0.98 (3H,t); 1.44-1.84 (2H,m); 2.61-3.18 (6H,m); 2.84 (6H, s); 3.93-4.42 (1H,m); 7.35-7.75 (3H,m); 8.03-8.30 (2H,m); 8.67-8.90 (1H,m); 18.42 (1H,s).

(h) 5-[4-Acetyl-2-methylnaphth-1-yl]-3-hydroxy-2-propionylcyclohex-2-en-1-one and 5-[4-acetyl-2,3-dimethylnaphth-1-yl]-3-hydroxy-2-propionylcyclohex-2-en-1-one.

A solution of 5-(2,3-dimethylnaphth-1-yl)-3-hydroxy-2-propionylcyclohex-2-en-1-one (1.7 g; 5.3 mmol) in 1,2-dichloroethane (5 ml) was added to a suspension of aluminium trichloride (2.2 g; 16.75 mmol) in 1,2-dichloroethane (10 ml) at 0° C. The mixture was stirred at 0° C. for 30 min and a solution of acetyl chloride (0.5 g; 6.36 mmol) in 1,2-dichloroethane (5 ml) was added. After stirring at 0° C. for 30 min and at room temperature for 2 hr, the mixture was poured into a cold aqueous 50% hydrochloric acid solution which was then stirred vigorously for 1 hr. The solution was extracted with dichloromethane and the organic phase was washed with water. The dried (MgSO₄) organic fraction was evaporated and the residue was purified by preparative thin-layer chromatography with dichloromethane/ethyl acetate (2:1 v/v) elution to give 5-[4-acetyl-2,3-dimethylnaphth- 1-yl]-3-hydroxy-2-propionylcyclohex-2-en-1-one as a yellow oil.

5-[4-Acetyl-2-methylnaphth-1-yl]-3-hydroxy-2-propionylcyclohex-2-en-1-one was similarly prepared from 3-hydroxy-5-(2-methylnaphth-1-yl)-2-propionylcyclohex-2-en-1-one and was obtained as a brown oil.

(i) 2-Butyryl-3-hydroxy-5-(2,3-dimethyl-4-nitronaphth-1-yl)cyclohex-2-en-1-one

A mixture of fuming nitric acid (0.42), glacial acetic acid (0.27 g) and acetic anhydride (0.27 g) was added dropwise to a solution of 2-butyryl-5-(2,3-dimethylnaphth-1-yl)-3-hydroxy cyclohex-2-en-1-one (1.5 g) in acetic anhydride (8 ml) at 0° C. The mixture was stirred for 1 hr at 5°-10° C. and at 50° C. for 10 min. The cooled mixture was poured into water (150 ml) which was subsequently extracted with ether. The organic fraction was washed successively with a saturated sodium bicarbonate solution and with water. The dried (Na₂ SO₄) organic extract was evaporated under reduced pressure and the residue was purified by column chromatography over silica with dichloromethane elution to give 2-butyryl-3-hydroxy-5-(2,3-dimethyl-4-nitronapth-1-yl)cyclohex-2-en-1-one a yellow foam. Pmr spectrum (CDCl₃ ; δ in ppm): 1.03 (3H,t); 1.49-1.89 (2H,m); 2.40-3.89 (6H,m); 2.37 (3H,s); 2.52 (3H,s); 4.06-4.69 (1H,m); 7.32-7.66 (3H,m); 8.00-8.29 (1H,m); 18.38 (1H,s).

(j) 3-Hydroxy-2-propionyl-5-(quinolin-4-yl-1-oxide)-cyclohex-2-en-1-one

A solution of 3-chloroperoxybenzoic acid (100 mg) and 3-hydroxy-2-propionyl-5-(quinolin-4-yl)cyclohex-2-en-1-one (150 mg) in chloroform (10 ml) was kept at 20° C. for 20 hrs and was then washed with a dilute aqueous sodium bicarbonate solution (400 mg in 20 ml). The dried (MgSO₄) organic layer was evaporated under reduced pressure to give 3-hydroxy-2-propionyl-5-(quinolin-4-yl-1-oxide)cyclohex-2-en-1-one as a pale yellow oil (120 mg). Pmr spectrum (CDCl₃ ; δ in ppm): 1.16 (3H,t); 2.6-3.3 (6H,m); 3.9-4.3 (1H,m); 7.0-8.1 (4H,m); 8.4-8.9 (2H,m); 18.1 (1H,brs).

All products were characterized by proton nuclear magnetic resonance spectroscopy. Physical data and spectroscopic data for the 2-acyl-5-(aryl or heteroaryl)-3-hydroxycyclohex-2-en-1-one derivatives of formula XIII prepared according to any of the methods (a) to (f) above are recorded in Table 2 below. The specific Method used for the preparation of each 2-acyl-5-(aryl or heteroaryl)-3-hydroxycyclohex-2-en-1-one derivative of formula XIII is indicated in Table 3, Example 6.

                  TABLE 2                                                          ______________________________________                                          ##STR18##                    XIII                                             ______________________________________                                    

For convenience the 2-acyl-5-(aryl or heteroaryl)-3-hydroxycyclo-hex-2-en-1-one derivatives are tabulated according to structural type.

                  TABLE 2a                                                         ______________________________________                                          ##STR19##                                                                                                     Proton Chemical Shift                          X      X.sup.1                                                                              R.sup.3  Appearance                                                                               δ in ppm (CDCl.sub.3)                    ______________________________________                                         Cl     H     C.sub.2 H.sub.5                                                                         Pale      1.16(3H,t); 1.8-3.9                                                  yellow    (15H,m); 2.41(3H,s);                                                 oil       18.28(1H,s).                                   Cl     H     n-C.sub.3 H.sub.7                                                                       Pale      1.00(3H,t); 1.57-3.91                                                yellow    (17H,m); 2.40(3H,s);                                                 oil       18.33(1H,s).                                   OCH.sub.3                                                                             H     C.sub.2 H.sub.5                                                                         Pale      1.16(3H,t); 1.8-3.9                                                  yellow    (15H,m); 2.33(3H,s);                                                 oil       3.91(3H,s); 18.24                                                              (1H,s).                                        OCH.sub.3                                                                             H     n-C.sub.3 H.sub.7                                                                       Pale      1.00(3H,t); 1.6-3.9                                                  yellow    (17H,m); 2.33(3H,s);                                                 oil       3.91(3H,s); 18.37(1H,s)                        OCH.sub.3                                                                             OH    n-C.sub.3 H.sub.7                                                                       Pale      1.00(3H,t); 1.5-3.8                                                  yellow    (16H,m); 2.57(3H,s);                                                 oil       3.96(3H,s); 4.94(1H,                                                           brs); 18.37(1H,s).                             ______________________________________                                    

                  TABLE 2b                                                         ______________________________________                                          ##STR20##                                                                                                  Proton Chemical Shift                             (X.sup.1).sub.n.sup.1                                                                   R.sup.3 Appearance  δ in ppm (CDCl.sub.3)                       ______________________________________                                         6-CH.sub.3                                                                              C.sub.2 H.sub.5                                                                        Colourless  1.15(3H,t); 2.51(3H,                                               solid,      s); 2.8-3.9(7H,m);                                                 mp 130° C.                                                                          7.0-8.1(5H,m); 18.15                                                           (1H,s).                                           ______________________________________                                    

                  TABLE 2c                                                         ______________________________________                                          ##STR21##                                                                                                  Proton Chemical Shift                             (X).sub.n                                                                               R.sup.3  Appearance δ in ppm (CDCl.sub.3)                       ______________________________________                                         all H    C.sub.2 H.sub.5                                                                         White solid                                                                               1.18(3H,t); 2.78-4.30                                                          (7H,m); 7.3-8.1(7H,m);                                                         18.30(1H,s).                                      all H    n-C.sub.3 H.sub.7                                                                       Not recorded                                                 2-CH.sub.3                                                                              C.sub.2 H.sub.5                                                                         Pale yellow                                                                               1.18(3H,t); ca 2.6-                                                 oil        4.5(7H,m); 2.55(3H,s);                                                         7.37-8.21(6H,m); 18.34                                                         (1H,s).                                           4-CH.sub.3                                                                              n-C.sub.3 H.sub.7                                                                       Pale yellow                                                                               1.03(3H,t); 1.71(2H,                                                oil        m); 2.70(3H,s); ca                                                             2.7-4.3(7H,m); 7.3-                                                            8.1(6H,m); 18.37(1H,                                                           s).                                               2-OCH.sub.3                                                                             n-C.sub.3 H.sub.7                                                                       Brown solid,                                                                              1.03(3H,t); 1.72(2H,m);                                             mp 116° C.                                                                         2.4-4.4(7H,m); 3.95(3H,                                                        s); 7.2-8.1(6H,m);                                                             18.39(1H,brs).                                    4-OCH.sub.3                                                                             n-C.sub.3 H.sub.7                                                                       Brown solid,                                                                              1.03(3H,t); 1.69(2H,                                                mp 104° C.                                                                         m); 2.3-4.4(7H,m);                                                             3.96(3H,s); 6.63-8.4                                                           (6H,m); 18.34(1H,brs).                            2,3-     n-C.sub.3 C.sub.7                                                                       Pale yellow                                                                               1.03(3H,t); 1.68(2H,m);                           (CH.sub.3).sub.2  oil        2.45(6H,s); 2.5-4.0                                                            (6H,m); 4.29(1H,m);                                                            7.2-8.2(5H,m); 18.36                                                           (1H,s).                                           2,4-     C.sub.2 H.sub.5                                                                         Brown oil  1.19(3H,t); 2.50(3H,                              (CH.sub.3).sub.2             s); 2.61(3H,s); 2.5-                                                           4.5(7H,m); 7.12(1H,s);                                                         7.3-8.2(4H,m); 18.34                                                           (1H,s).                                           2,4-     n-C.sub.3 H.sub.7                                                                       Brown oil  1.03(3H,t); 1.72(2H,                              (CH.sub.3).sub.2             m); 2.51(3H,s); 2.63                                                           (3H,s); 2.5-4.4(7H,m);                                                         7.15(1H,s); 7.3-8.3                                                            (4H,m); 18.42(1H,s).                              2-Br-    n-C.sub.3 H.sub.7                                                                       Not recorded                                                                              1.03(3H,t); 1.70(2H,                              4-CH.sub.3                   m); 2.64(3H,s); 2.6-                                                           4.8(7H,m); 7.5-8.3                                                             (5H,m); 18.39(1H,s).                              2-       n-C.sub.3 H.sub.7                                                                       White solid,                                                                              1.03(3H,t); 1.72(2H,                              OCH.sub.3         mp 149° C.                                                                         m); 2.70(3H,s); 2.6-                              4-CH.sub.3                   4.4(7H,m); 3.96(3H,s);                                                         7.15(1H,s); 7.3-8.1                                                            (4H,m); 18.38(1H,s).                              3,4-     C.sub.2 H.sub.5                                                                         Brown oil  1.19(3H,t); 2.47(3H,                              (CH.sub.3).sub.2             s); 2.58(3H,s); 2.6-                                                           4.3(7H,m); 7.15(1H,s);                                                         7.4-8.2(4H,m); 18.31                                                           (1H,s).                                           2,3,4-   n-C.sub.3 H.sub.7                                                                       Yellow oil 1.03(3H,t); 1.74(2H,                              (CH.sub.3).sub.3             m); 2.20-4.60(7H,m);                                                           2.43(3H,s); 2.50(3H,                                                           s); 2.64(3H,s); 7.36-                                                          7.46(2H,m); 8.04-8.21                                                          (2H,m); 18.30(1H,s).                              ______________________________________                                    

                  TABLE 2d                                                         ______________________________________                                          ##STR22##                                                                                                    Proton Chemical Shift                           (X).sub.n                                                                            (X.sup.1).sub.n.sup.1                                                                  R.sup.3 Appearance                                                                              δ in ppm (CDCl.sub.3)                     ______________________________________                                         all H all H   C.sub.2 H.sub.5                                                                        Pale     1.16(3H,t); 2.72-3.67                                                 yellow   (7H,m); 7.2-7.9(7H,m);                                                solid,   18.25(1H,s).                                                          mp 125° C.                                        3-CH.sub.3                                                                           all H   C.sub.2 H.sub.5                                                                        Pale     1.16(3H,t); 2.48(3H,                                                  yellow   s); 2.68-3.00(4H,m);                                                  solid,   3.04-3.24(2H,q); 3.48-                                                mp 118° C.                                                                       3.84(1H,m); 7.32-7.76                                                          (6H,m); 18.24(1H,s).                            all H 6-CH.sub.3                                                                             n-C.sub.3 H.sub.7                                                                      White    0.98(3H,t); 1.68(2H,                                                  solid,   m); 2.48(3H,s); 3.00                                                  mp 122° C.                                                                       (3H,m); 2.64-2.96(4H,                                                          m); 3.36(1H,m); 6.88-                                                          7.36(2H,m); 7.44-7.84                                                          (4H,m); 18.24(1H,s).                            1,4-  all H   n-C.sub.3 H.sub.7                                                                      Oil      1.03(3H,s); 1.69(2H,                            (CH.sub.3).sub.2               m); 2.65(3H,s); 2.70                                                           (3H, s); 2.7-4.0(7H,m);                                                        7.19(1H,s); 7.5-8.1                                                            (4H,m); 18.37(1H,s).                            1,3,4-                                                                               all H   n-C.sub.3 H.sub.7                                                                      Pale     1.03(3H,s); 1.71(2H,                            (CH.sub.3).sub.3      yellow   m); 2.53(3H,s); 2.64                                                  oil      (3H,s); 2.64(3H,s);                                                            2.6-4.4(7H,m); 7.4-                                                            8.2(4H,m); 18.39(1H,s)                          ______________________________________                                    

                  TABLE 2e                                                         ______________________________________                                          ##STR23##                                                                                                     Proton Chemical Shift                          (X).sub.n                                                                            R.sup.4  R.sup.3 Appearance                                                                              δ in ppm (CDCl.sub.3)                    ______________________________________                                         5,6,7-                                                                               CO.sub.2 CH.sub.3                                                                       n-C.sub.3 H.sub.7                                                                      Brown    1,02(3H,t); 1.72(2H,                           (CH.sub.3).sub.3       oil      m); 2.44(3H,s); 2.57                                                           (6H,s); 2.4-4.2(6H,m);                                                         3.44(3H,s); 7.3-8.8                                                            (3H,m); 18.42(1H,s).                           5,6,7-                                                                               H        n-C.sub.3 H.sub.7                                                                      Yellow   1.03(3H,t); 1.72(2H,                           (CH.sub.3).sub.3       oil      m); 2.44(3H,s); 2.51                                                           (3H,s); 2.58(3H,s);                                                            2.4-4.9(7H,m); 7.3-                                                            8.8(3H,m); 18.41(1H,s)                         ______________________________________                                    

                  TABLE 2f                                                         ______________________________________                                          ##STR24##                                                                                           Proton Chemical shift                                    R.sup.3 Appearance    δ in ppm (CDCl.sub.3)                              ______________________________________                                         n-C.sub.3 H.sub.7                                                                      Clear oil     1.01(3H,t); 1.70(2H,m);                                                        2.3-4.2(7H,m); 7.3-8.9(6H,                                                     m); 18.36(1H,s).                                         ______________________________________                                    

                  TABLE 2g                                                         ______________________________________                                          ##STR25##                                                                                                Proton Chemical shift                               Z      R.sup.3                                                                               Appearance   δ in ppm (CDCl.sub.3)                         ______________________________________                                         --     C.sub.2 H.sub.5                                                                       Colourless   1.16(3H,t); 2.6-3.3(6H,                                           solid        m); 3.9-4.3(1H,m); 7.1-                                                        8.2(5H,m); 8.85(1H,d);                                                         18.0(1H,brs).                                       ______________________________________                                    

EXAMPLE 5

The compounds of the invention of formula I indicated in Table 3 were prepared from the appropriate 2-acyl-5-(aryl or heteroaryl)-3-hydrocyclohex-2-en-1-one derivatives of formula XIII and the appropriate hydroxylamine hydrochloride derivative either by Method (a) or Method (b) below.

(a) A mixture of 2-butyryl-5-(3-chloro-1-methyl-5,6,7,8-tetrahydroisoquinolin-4-yl)-3-hydroxycyclohex-2-en-1-one (2.07 g), ethoxyamine hydrochloride (1.1 equiv), sodium hydroxide (1.1 equiv in 0.5 ml water) and ethanol (40 ml) was stirred at room temperature for 3 hr. The mixture was poured into a very dilute hydrochloric acid solution, which was then immediately extracted with diethyl ether. The dried (MgSO₄) organic extract was evaporated to give 5-(3-chloro-1-methyl-5,6,7,8-tetrahydroisoquinolin-4-yl-2-[1-(ethoxyimino)butyl]-3-hydroxycyclohex-2-en-1-one as a white solid, mp 141° C. The product was characterized by proton nuclear magnetic resonance spectroscopy and the spectroscopic data is recorded in Table 4, Example 10.

(b) A mixture of 2-butyryl-5-(1,4-dimethylnaphth-2-yl)-3-hydroxycyclohex-2-en-1-one (0.25 g), ethoxyamine hydrochloride (1.3 equiv) and sodium acetate trihydrate (1.3 equiv) were stirred in ethanol (30 ml) at room temperature for 4 hr. The mixture was then immediately extracted with ether. The dried (MgSO₄) organic extract was evaporated to give 5-(1,4-dimethylnaphth-2-yl)-2-[1-(ethoxyimino)butyl]-3-hydroxycyclohex-2-en-1-one as a pale yellow oil. The product was characterized by proton nuclear magnetic resonance spectroscopy and the spectroscopic data is recorded in Table 4, Example 10.

EXAMPLE 6

The specific Method employed for the preparation of each of the 1-(aryl or heteroaryl)but-1-en-3-one derivatives of formula VI (Example 3), the 5-(aryl or heteroaryl)-3-hydroxy cyclohex-2-en-1-one derivatives of formula IX (Example 4) and/or the 2-acyl-5-(aryl or heteroaryl)-3-hydroxycyclohex-2-en-1-one derivatives of formula XIII (Example 4) used as intermediates in the preparation of the compounds of the invention of formula I are listed in Table 3 below together with the specific Method employed for the preparation of the compounds of the invention of formula I (Example 5).

Each of the compounds of the invention of formula I were characterized by proton nuclear magnetic resonance spectroscopy and physical data and spectroscopic data are recorded in Table 4, Example 10.

                  TABLE 3                                                          ______________________________________                                         Method of Preparation of Compounds of                                          Formulae:                                                                              VI            VIII      I                                              Compound                                                                               Example 3     Example 4 Example 5                                      No      Method        Method    Method                                         ______________________________________                                         10      a             c         a                                              11      a             d         a                                              12      a             d         a                                              13      a             e         a                                              14      a             b         a                                              15      a             b         a                                              16      a             a         b                                              17      a             f         b                                              18      a             f         b                                              19      a             f         b                                              20      a             g         b                                              21      a             a         b                                              22      a             a         b                                              23      a             a         b                                              24      a             a         b                                              25      a             a         b                                              28      a             h         b                                              29      a             f         b                                              30      a             f         b                                              31      a             a         b                                              32      a             h         b                                              33      a             i         b                                              34      a             f         b                                              35      a             f         b                                              36      b             e         a                                              37      a             a         b                                              38      a             a         a                                              39      b             a         b                                              40      a             a         b                                              41      a             a         a                                              42      a             a         b                                              43      a             a         b                                              44      a             a         b                                              46      a             a         a                                              47      a             a         a                                              48      a             a         a                                              50      b             f         b                                              51      b             j         b                                              52      b             a         b                                              ______________________________________                                    

EXAMPLE 7

2-[1-(Ethoxyimino)butyl]-3-hydroxy-5-(3-methoxy-1-methyl-8-oxo-5,6,7,8-tetrahydroisoquinolin-4-yl)-cyclohex-2-en-1-one (49)

Pyridinium chlorochromate (1.1 equiv) was added in small portions to a stirred solution of 2-[1-(ethoxyimino)butyl]-3-hydroxy-5-(8-hydroxy-3-methoxy-1-methyl-5,6,7,8-tetrahydroisoquinolin-4-yl)cyclohex-2-en-1-one (0.1 g) in dichloromethane (40 ml) at room temperature. The mixture was filtered through a small silica chromatography column with dichloromethane/ethyl acetate (5:1 v/v) elution to give 2-[1-(ethoxyimino)butyl]-3-hydroxy-5-(3-methoxy-1-methyl-8-oxo-5,6,7,8-tetrahydroisoquinolin-4-yl)cyclohex-2-en-1-one as a white solid, mp 162° C. The product was characterized by proton nuclear magnetic resonance spectroscopy and the spectroscopic data is recorded in Table 4, Example 10.

EXAMPLE 8

Sodium salt of 5-[3-chloro-1-methyl-5,6,7,8-tetrahydroisoquinolin-4-yl]-2-[1-(ethoxyimino)butyl]-3-hydroxycyclohex-2-en-1-one (45) and sodium salt of 5-(2,4-dimethylnaphth-1-yl)-2-[1-(ethoxyimino)butyl]-3-hydroxycyclohex-2-en-1-one (27).

(a) A mixture of 5-[3-chloro-1-methyl-5,6,7,8-tetrahydroisoquinolin-4-yl]-2-[1-(ethoxyimino)butyl]-3-hydroxycyclohex-2-en-1-one (0.4 g), aqueous sodium hydroxide (1 equiv in 2 ml) and toluene (60 ml) was evaporated under reduced pressure. Toluene (60 ml) was added to the residue and the mixture was heated and evaporated under reduced pressure. The residue was washed with ether leaving the sodium salt of 5-[3-chloro-1-methyl-5,6,7,8-tetrahydroisoquinolin-4-yl]-2-[1-(ethoxyimino)butyl]-3-hydroxycyclohex-2-1-one as a pale yellow solid, mp >210° C. (dec).

(b) The sodium salt of 5-(2,4-dimethylnaphth-1-yl)-2-[1-(ethoxyimino)butyl]-3-hydroxycyclohex-2-en-1-one was prepared from 5-(2,4-dimethylnaphth-1-yl)-2-[1-(ethoxyimino)butyl]-3-hydroxycyclohex-2-en-1-one following essentially the same procedure as that described above. The product was obtained as a light brown solid, mp >220° C. (dec).

EXAMPLE 9

3-Benzoyloxy-5-(2,4-dimethylnaphth-1-yl)-2-[1-ethoxyimino)butyl]cyclohex-2-en-1-one (26)

A slight excess of benzoyl chloride was added to a suspension of the sodium salt of 5-(2,4-dimethylnaphth-1-yl)-2-[1-(ethoxyimino)butyl]-3-hydroxycyclohex-2-en-1-one (0.34 g) in acetone (20 ml) and the mixture was stirred at room temperqature for 12 hr. The mixture was filtered, the filtrate was evaporated and the residue was purified by column chromatography over silica with dichloromethane elution to give 3-benzoyloxy-5-(2,4-dimethylnaphth-1-yl)-2-[1-(ethoxyimino)butyl]cyclohex-2-en-1-one as a pale yellow oil. The product was characterized by proton nuclear magnetic resonance spectroscopy and the spectroscopic data is recorded in Table 4, Example 10.

EXAMPLE 10

The compounds of the invention of formula I were characterized by and may be identified by their proton nuclear magnetic resonance spectra. For convenience physical data and pmr spectroscopic data for the compounds of the invention of formula I are recorded in Table 4 below.

                  TABLE 4                                                          ______________________________________                                         Compound               Proton Chemical Shift                                   No         Appearance  δ in ppm (CDCl.sub.3)                             ______________________________________                                         10         White solid,                                                                               1.13-1.43(6H,2xt); ca                                              mp 94° C.                                                                           3.0(7H,n); 4.14(2H,q);                                                         7.40-8.02(7H,m); 15.15                                                         (1H,s).                                                 11         Pale yellow 1.02(3H,t); 1.33(3H,t);                                            solid, mp   ca 1.62(2H,m); ca 2.9                                              108° C.                                                                             (7H,m); 4.13(2H,q);                                                            7.36-8.12(7H,m); 15.25                                                         (1H,s).                                                 12         Not         1.11-1.39(6H,2xt); 2.71-                                           recorded    3.44(7H,m); 4.07(2H,q);                                                        7.3-7.81(7H,m); 14.96                                                          (1H,s).                                                 13         Oil         1.22(3H,t); 1.31(3H,t);                                                        2.48(3H,s); 2.72-2.97                                                          (4H,m); 2.97-3.12(2H,q);                                                       3.44-3.80(1H,m); 3.98-                                                         4.22(2H,q); 7.20-7.76(6H,                                                      m); 15.08(1H,s).                                        14         Pale yellow 1.03(3H,t); 1.33(3H,t);                                            oil         1.71(2H,m); 2.45(6H,s);                                                        2.5-4.0(6H,m); 4.13(2H,                                                        q); 4.25(1H,m); 7.2-8.2                                                        (5H,m); 15.12(1H,s).                                    15         Light yellow                                                                               1.03(3H,t); 1.34(3H,t);                                            solid, mp   1.64(2H,m); 2.10-4.60                                              120° C.                                                                             (9H,m); 2.43(3H,s); 2.50                                                       3H,s); 2.64(3H,s); 7.36-                                                       7.46(2H,m); 8.04-8.21(2H,                                                      m); 15.12(1H,s).                                        16         Pale yellow 1.15-1.41(6H,2xt); ca                                              oil         2.6-3.9(7H,m); 2.56(3H,                                                        s); 4.06(2H,q); 7.35-8.26                                                      (6H,m); 15.11(1H,brs).                                  17         Pale yellow 1.03(3H,t); 1.33(3H,t);                                            solid, mp   1.64(2H,m); 2.67(3H,s);                                            118° C.                                                                             2.6-4.2(7H,m); 4.12(2H,                                                        q); 7.3-8.2(6H,m); 15.22                                                       (1H,brs).                                               18         Not recorded                                                                               1.04(3H,t); 1.30(3H,t);                                                        1.71(2H,m); 2.4-4.5(7H,                                                        m); 3.89(3H,s); 4.10(2H,                                                       q); 7.2-8.1(6H,m); 15.03                                                       (1H,brs).                                               19         Brown solid,                                                                               1.02(3H,t); 1.32(3H,t);                                            mp 70° C.                                                                           1.64(2H,m); 2.4-4.5(7H,                                                        m); 3.99(3H,s); 4.12(2H,                                                       q); 6.7-8.4(6H,m); 15.19                                                       (1H,brs).                                               20         Pale yellow 1.02(3H,t); 1.15-1.83(5H,                                          oil         m); 2.67-3.10(6H,m);                                                           2.84(6H,s); 3.90-4.30(3H,                                                      m); 7.35-7.69(3H,m);                                                           8.03-8.41(2H,m); 8.55-                                                         8.95(1H,m); 15.27(1H,s).                                21         Brown oil   1.16-1.42(6H,2xt); 2.53-                                                       (3H,s); 2.64(3H,s); 2.5-                                                       4.3(7H,m); 4.14(2H,q);                                                         7.15(1H,s); 7.39-8.26                                                          (4H,m); 15.01(1H,s).                                    22         Brown oil   1.06(3H,t); 1.38(3H,t);                                                        1.66(2H,m); 2.56(3H,s);                                                        2.67(3H,s); 2.5-4.3(7H,                                                        m); 4.19(2H,q); 7.19(1H,                                                       s); 7.4-8.3(4H,m); 15.18                                                       (1H,brs)                                                23         Brown oil   1.03(3H,t); 1.66(2H,m);                                                        2.53(3H,s); 2.64(3H,s);                                                        2.5-4.3(7H,m); 4.56(2H,                                                        d); 5.3-6.2(3H,m); 7.16                                                        (1H,s); 7.4-8.3(4H,m);                                                         OH not observed                                         24         Brown oil   1.02(3H,t); 1.68(2H,m);                                                        2.53(3H,s); 2.65(3H,s);                                                        ca 2.0-4.3(8H,m); 4.68                                                         (2H,d); 7.16(1H,s); 7.4-                                                       8.3(4H,m); OH not                                                              observed.                                               25         Orange oil  1.02(3H,t); 1.66(2H,m);                                                        2.53(3H,s); 2.65(3H,s);                                                        2.5-3.8(7H,m); 4.1-5.0                                                         (4H,m); 7.17(1H,s); 7.4-                                                       8.3(4H,m); OH not                                                              observed.                                               26         Pale yellow 0.89-1.21(6H,2xt); 1.55                                            oil         (2H,m); 2.56(3H,s); 2.62                                                       (3H,s); ca 2.5-4.7(7H,                                                         m); 4.05(2H,q); 7.16(1H,                                                       s); 7.3-8.9(9H,m).                                      28         Pale yellow 1.18-1.43(9H,3xt); 2.34                                            oil         (3H,s); 2.58(3H,s); 2.5-                                                       4.0(7H,m); 4.07-4.45(4H,                                                       2xq); 7.35(1H,s); 7.5-                                                         8.4(4H,m); 15.05(1H,brs).                               29         Not recorded                                                                               1.03(3H,t); 1.34(3H,t);                                                        1.66(2H,m); 2.63(3H,s);                                                        2.6-4.8(7H,m); 4.14(2H,                                                        q); 7.5-8.3(5H,m); 15.18                                                       (1H,brs).                                               30         Pale yellow 1.03(3H,t); 1.33(3H,t);                                            oil         1.66(2H,m); 2.4-4.2(7H,                                                        m); 2.69(3H,s); 3.94(3H,                                                       s); 4.12(2H,q); 7.14(1H,                                                       s); 7.3-8.1(4H,m); 15.03                                                       (1H,brs).                                               31         Pale yellow 1.13-1.41(6H,2xt); 2.48                                            solid,      (3H,s); 2.59(3H,s); 2.6-                                           mp 110° C.                                                                          4.2(7H,m); 4.13(2H,q);                                                         7.18(1H,s); 7.4-8.2(4H,                                                        m); 15.11(1H,brs).                                      32         Yellow oil  1.12-1.46(9H,3xt); 2.15-                                                       4.5(16H,m); 4.02-4.4(4H,                                                       2xq); 7.1-8.4(4H,m);                                                           15.05(1H,brs).                                          33         Yellow foam 1.03(3H,t); 1.34(3H,t);                                                        1.49-1.92(2H,m); 2.40-                                                         4.69(7H,m); 2.37(3H,s);                                                        2.52(3H,s); 4.17(2H,q);                                                        7.32-7.55(3H,m); 7.90-                                                         8.39(1H,m); 15.26(1H,brs)                               34         Brown oil   1.02(3H,t); 1.33(3H,t);                                                        1.64(2H,m); 2.42(3H,s);                                                        2.55(3H,s); 2.57(3H,s);                                                        ca 2.4-4.2(6H,m); 3.40                                                         (3H,s); 4.12(2H,q); 7.3-                                                       8.8(3H,m); 15.39(1H,brs).                               35         Brown oil   1.03(3H,t); 1.32(3H,t);                                                        1.67(2H,m); ca 2.4-4.9                                                         (7H,m); 2.41(3H,s); 2.50                                                       (3H,s); 2.56(3H,s); 4.12                                                       (2H,q); 7.3-8.8(3H,s);                                                         14.47(1H,brs).                                          36         White solid,                                                                               0.99(3H,t); 1.28(3H,t);                                            mp 80° C.                                                                           1.56(2H,m); 2.48(3H,s);                                                        2.64-3.04(6H,m); 3.36(1H,                                                      m); 4.10(2H,q); 7.23-7.34                                                      (2H,m); 7.57-7.73(4H,m);                                                       15.21(1H,brs).                                          37         Oil         1.02(3H,t); 1.35(3H,t);                                                        1.64(2H,m); 2.67(6H,s);                                                        2.6-4.3(7H,m); 4.14(2H,                                                        q); 7.3(1H,s); 7.5-8.2                                                         (4H,m); OH not observed.                                38         White solid,                                                                               1.02(3H,t); 1.34(3H,t);                                            mp 108° C.                                                                          1.69(2H,m); 2.52(3H,s);                                                        2.63(3H,s); 2.75(3H,s);                                                        2.5-4.2(7H,m); 4.14(2H,                                                        q); 7.4-8.1(4H,m); 15.15                                                       (1H,brs).                                               39         Pale yellow oil                                                                            0.99(3H,t); 1.33(3H,t);                                                        1.61(2H,m); 2.3-4.5(7H,                                                        m); 4.12(2H,q); 7.3-9.0                                                        (6H,m); OH not observed                                 40         Pale yellow 1.11-1.41(6H,2xt); 1.8-                                            oil         3.9(15H,m); 2.40(3H,s);                                                        4.13(2H,q); 15.08(1H,brs)                               41         White solid,                                                                               1.00(3H,t); 1.33(3H,t);                                            141° C.                                                                             1.49-3.89(17H,m); 2.40                                                         (3H,s); 4.12(2H,q); OH                                                         not observed.                                           42         Pale yellow 1.00(3H,t); 1.5-3.9(17H,                                           oil         m); 2.40(3H,s); 4.55 2H,                                                       d); 5.27-6.3(3H,m); OH                                                         not observed.                                           43         Pale yellow 0.98(3H,t); 1.5-4.0(18H,                                           oil         m); 2.40(3H,s); 4.66(2H,                                                       d); OH not observed.                                    44         Pale yellow 0.99(3H,t); 1.4-4.0(17H,                                           oil         s); 2.40(3H,s); 4.1-4.9                                                        (4H,m); OH not observed.                                46         Pale yellow 1.10-1.40(6H,2xt); 1.8-                                            oil         3.9(15H,m); 2.33(3H,s);                                                        3.90(3H,s); 4.12(2H,q);                                                        14.89(1H,brs).                                          47         Pale yellow 1.00(3H,t); 1.32(3H,t);                                            oil         1.5-3.7(17H,m); 2.33(3H,                                                       s); 3.91(3H,s); 4.11(2H,                                                       q); OH not observed.                                    48         Pale yellow 1.00(3H,t); 1.32(3H,t);                                            oil         1.5-3.7(16H,m); 2.54(3H,                                                       s); 3.92(3H,s); 4.11(2H,                                                       q); 4.92(1H,brs); enolic                                                       OH not observed.                                        49         White solid,                                                                               1.01(3H,t); 1.33(3H,t);                                            mp 162° C.                                                                          1.5-3.7(15H,m); 2.75(3H,                                                       s); 4.00(3H,s); 4.12(2H,                                                       q); 15.15(1H,brs).                                      50         Pale yellow 1.21(3H,t); 1.34(3H,t);                                            solid       2.7-3.2(6H,m); 4.0-4.3                                                         (3H,m); 7.2-8.3(5H,m);                                                         8.87(1H,d), OH not                                                             observed.                                               51         Brown oil   1.20(3H,t); 1.35(3H,t);                                                        2.6-3.2(6H,m); 3.9-4.3                                                         (3H,m); 7.1-8.2(4H,m);                                                         8.4-8.9(2H,m); OH not                                                          observed.                                               52         Brown solid,                                                                               1.17(3H,t); 1.32(3H,t);                                            mp 82° C.                                                                           2.51(3H,s); 2.8-3.3(6H,                                                        m); 3.4-3.5(1H,m); 4.11                                                        (2H,q); 7.2-8.1(5H,m);                                                         15.04(1H,brs).                                          ______________________________________                                    

EXAMPLE 11

This non-limiting Example illustrates the preparation of formulations of the compounds of the invention.

(a) Emulsifiable Concentrate

Compound No. 15 was dissoloved in toluene containing 7% V/V "Teric" N13 and 3% v/v "Kemmat" SC15B to give an emulsifiable concentrate which may be diluted with water to the required concentration to give an aqueous emulsion which may be applied by spraying.

("Teric" is a Trade Mark and "Teric" N13, is a product of ethoxylation of nonylphenol; "Kemmat" is a Trade Mark and "Kemmat" SC15B is a formulation of calcium dodecylbenzenesulfonate.)

(b) Aqueous Suspension

Compound No. 15 (5 parts by weight) and "Dyapol" PT (1 part by weight) were added to an aqueous solution (94 parts by weight) of "Teric" N8 and the mixture was ball milled to produce a stable aqueous suspension which may be diluted with water to the required concentration to give an aqueous suspension which may be applied by spraying ("Dyapol" is a Trade Mark and "Dyapol" PT is an anionic suspending agent; "Teric" N8 is a product of ethoxylation of nonylphenol).

(c) Emulsifiable Concentrate

Compound No. 15 (10 parts by weight), "Teric" N13 (5 parts by weight) and "Kemmat" SC15B (5 parts by weight) were dissolved in "Solvesso" 150 (80 parts by weight) to give an emulsifiable concentrate which may be diluted with water to the required concentration to give an aqueous emulsion which may be applied by spraying. ("Solvesso" is a Trade Mark and "Solvesso" 150 is a high boiling point aromatic petroleum fraction.)

(d) Dispersible Powder

Compound No. 15 (10 parts by weight), "Matexil" DA/AC (3 parts by weight), "Aerosol" OT/B (1 part by weight) and china clay 298 (86 parts by weight) were blended and then milled to give a powder composition having a particle size below 50 microns ("Matexil" is a Trade Mark and "Matexil" DA/AC is the disodium salt of a naphthalenesulfonic acid/formaldehyde condensate; "Aerosol" is a Trade Mark and "Aerosol" OT/B is a formulation of the dioctyl ester of sodium sulfosuccinic acid.)

(e) High Stength Concentrate

Compound No. 15 (99 parts by weight), silica aerogel (0.5 parts by weight) and synthetic amorphous silica (0.5 parts by weight) were blended and ground in a hammer-mill to produce a powder having a particle size less than 200 microns.

(f) Dusting Powder

Compound No. 15 (10 parts by weight), attapulgite (10 parts by weight) and pyrophyllite (80 parts by weight) were thoroughly blended and then ground in a hammer-mill to produce a powder of particle size less than 200 microns.

Emulsifiable concentrates and/or suspensions of the compounds of the invention were prepared essentially as described in part (a), (b) or (c) above and then diluted with water, optionally containing surface active agent and/or oil, to give aqueous compositions of the required concentration which were used, as described in Examples 12 and 13, in the evaluation of the pre-emergence and post-emergence herbicidal activity of the compounds.

EXAMPLE 12

The pre-emergent herbicidal activity of the compounds of the invention formulated as described in Example 11 was assessed by the following procedure:

The seeds of the test species were sown in rows 2 cm deep in soil contained in seed boxes. The monocotyledonous plants and the dicotyledonous plants were sown in separate boxes and after sowing the two boxes were sprayed with the required quantity of a composition of the invention. Two duplicate seed boxes were prepared in the same manner but were not sprayed with a composition of the invention and were used for comparison purposes. All the boxes were placed in a glasshouse, lightly watered with an overhead spray to initiate germination and then sub-irrigated as required for optimum plant growth. After three weeks the boxes were removed from the glass house and the effect of the treatment was visually assessed. The results are presented in Table 5 where the damage to plants is rated on a scale of from 0 to 5 where 0 represents from 0 to 10% damage, 1 represents from 11 to 30% damage, 2 represents from 31 to 60% damage, 3 represents from 61 to 80% damage, 4 represents from 81 to 99% damage and 5 represents 100% kill. A dash (-) means that no experiment was carried out.

The names of the test plants are as follows:

    ______________________________________                                                Wh         Wheat                                                               Ot         Wild Oats                                                           Rg         Ryegrass                                                            Jm         Japanese millet                                                     P          Peas                                                                Ip         Ipomea                                                              Ms         Mustard                                                             Sf         Sunflower                                                    ______________________________________                                    

                  TABLE 5                                                          ______________________________________                                         PRE-EMERGENCE HERBICIDAL ACTIVITY                                              Com-                                                                           pound  APPLICATION  TEST PLANT                                                 No     Rate (kg/ha) Wh     Ot  Rg  Jm  P   Ip  Ms  Sf                          ______________________________________                                         10     1.0          0      1   4   5   0   0   0   0                           10     0.25         0      0   3   4   0   0   0   0                           16     1.0          0      0   5   5   0   0   0   0                           16     0.25         0      0   5   5   0   0   0   0                           18     1.0          1      1   4   3   0   0   0   0                           21     1.0          0      3   4   5   0   0   0   0                           22     1.0          0      4   5   5   0   0   0   0                           40     1.0          0      0   5   5   0   0   0   0                           41     1.0          0      1   4   5   0   0   0   0                           46     1.0          0      0   4   2   0   0   0   0                           47     1.0          0      0   5   5   0   0   0   0                           48     1.0          4      5   5   5   0   0   0   0                           48     0.25         3      5   5   5   0   0   0   0                           49     1.0          5      5   5   5   0   0   0   0                           49     0.25         0      4   4   3   0   0   0   0                           52     1.0          0      0   5   5   0   0   0   0                           ______________________________________                                    

EXAMPLE 13

The post-emergent herbicidal activity of the compounds of the invention formulated as described in Example 11 was assessed by the following procedure.

The seeds of the test species were sown in rows 2 cm deep in soil contained in seed boxes. The monocotyledonous plants and the dicotyledonous plants were sown in separate seed boxes in duplicate. The four seed boxes were placed in a glass house, lightly watered with an overhead spray to initiate germination and then sub-irrigated as required for optimum plant growth. After the plants had grown to a height of about 10 to 12.5 cm one box of each of the monocotyledonous plants and the dicotyledonous plants was removed from the glass house and sprayed with the required quantity of a composition of the invention. After spraying the boxes were returned to the glass house for a further 3 weeks and the effect of treatment was visually assessed by comparison with the untreated controls. The results are presented in Table 6 where the damage to plants is rated on a scale of from 0 to 5 where 0 represents from 0 to 10% damage, 1 represents from 11 to 30% damage, 2 represents from 31 to 60% damage, 3 represents from 61 to 80% damage, 4 represents from 81 to 99% damage and 5 represents 100% kill. A dash (-) means that no experiment was carried out.

The names of the test plants are as follows:

    ______________________________________                                                Wh         Wheat                                                               Ot         Wild Oats                                                           Rg         Ryegrass                                                            Jm         Japanese millet                                                     P          Peas                                                                Ip         Ipomea                                                              Ms         Mustard                                                             Sf         Sunflower                                                    ______________________________________                                    

                  TABLE 6                                                          ______________________________________                                         POST-EMERGENCE HERBICIDAL ACTIVITY                                             Com-                                                                           pound  APPLICATION  TEST PLANT                                                 No     Rate (kg/ha) Wh     Ot  Rg  Jm  P   Ip  Ms  Sf                          ______________________________________                                         10     2.0          0      0   5   4   0   0   0   0                           10     0.5          0      0   3   3   0   0   0   0                           11     2.0          0      0   5   4   0   0   0   0                           11     0.5          0      0   2   3   0   0   0   0                           12     2.0          1      4   5   5   0   0   0   0                           12     0.5          1      1   4   4   0   0   0   0                           13     2.0          0      0   5   3   0   0   0   0                           14     1.0          0      2   4   3   0   0   0   0                           15     1.0          3      5   5   5   0   0   0   0                           15     0.25         0      5   5   5   0   0   0   0                           15     0.063        0      5   --  5   0   0   0   0                           16     1.0          1      5   5   5   0   0   0   0                           16     0.25         0      3   5   5   0   0   0   0                           21     1.0          1      5   5   5   0   0   0   0                           21     0.25         0      5   5   5   0   0   0   0                           21     0.063        0      5   0   5   0   0   0   0                           22     1.0          2      5   5   5   0   0   0   0                           22     0.25         0      5   5   5   0   0   0   0                           22     0.063        0      5   3   5   0   0   0   0                           23     1.0          1      5   5   5   0   0   0   0                           25     1.0          0      5   5   5   0   0   0   0                           25     0.25         0      5   --  5   0   0   0   0                           26     1.0          0      5   3   5   0   0   0   0                           32     1.0          3      5   5   5   0   0   0   0                           32     0.25         2      4   3   5   0   0   0   0                           40     1.0          4      5   5   5   0   0   0   0                           40     0.25         2      5   5   5   0   0   0   0                           40     0.063        1      5   5   5   0   0   0   0                           41     1.0          3      5   5   5   0   0   0   0                           41     0.25         0      5   5   5   0   0   0   0                           46     1.0          4      5   5   5   0   0   0   0                           46     0.25         3      5   5   5   0   0   0   0                           46     0.063        0      5   4   5   0   0   0   0                           47     1.0          5      5   5   5   0   0   0   0                           47     0.25         1      5   5   5   0   0   0   0                           47     0.063        0      5   5   5   0   0   0   0                           48     1.0          5      5   5   5   0   0   0   0                           48     0.25         5      5   5   5   0   0   0   0                           48     0.063        2      5   4   5   0   0   0   0                           49     1.0          5      5   5   5   0   0   0   0                           49     0.25         4      5   4   5   0   0   0   0                           ______________________________________                                    

EXAMPLE 14

The compounds were formulated for test by mixing an appropriate amount with 5 ml of an emulsion prepared by diluting 160 ml of a solution containing 21.9 g per liter of "Span" 80 and 78.2 g per liter of "Tween" 20 in methylcyclohexanone to 500 ml with water. "Span" 80 is a Trade Mark for a surface-active agent comprising sorbitan monolaurate. "Tween" 20 is a Trade Mark for a surface-active agent comprising a condensate of sorbitan monolaurate with 20 molar proportions of ethylene oxide. Each 5 ml emulsion containing a test compound was then diluted to 40 ml with water and sprayed on to young pot plants (post-emergence test) of the species named in Table 7 below. Damage to test plants was assessed after 14 days on a scale of 0 to 5 wherein 0 is 0 to 20% damage and 5 is complete kill. In a test for pre-emergence herbicidal activity, seeds of the test plants were sown in a shallow slit formed in the surface of soil in fibre trays. The surface was then levelled and sprayed, and fresh soil then spread thinly over the sprayed surface. Assessment of herbicidal damage was carried out after 21 days using the same scale of 0 to 5 as the post-emergence test. In both cases the degree of herbicidal damage was assessed by comparison with untreated control plants. the results are given in Table 7 below. A dash (-) means no experiment was carried out.

The names of the test plants were as follows:

    ______________________________________                                         Sb              Sugar beet                                                     Rp              Rape                                                           Ct              Cotton                                                         Sy              Soy bean                                                       Mz              Maize                                                          Ww              Winter wheat                                                   Rc              Rice                                                           Br              Barley                                                         Sn              Senecio vulgaris                                               Ip              Ipomea purpurea                                                Am              Amaranthus retroflexus                                         Pi              Polygonum album                                                Ca              Chenopodium album                                              Ga              Galium aparine                                                 Xa              Xanthium pensylvanicum                                         Ab              Abutilon theophrasti                                           Co              Cassia obtusifolia                                             Av              Avena fatua                                                    Dg              Digitaria sanguinalis                                          Al              Alopecurus myosuroides                                         St              Setaria viridis                                                Ec              Echinochloa crus-galli                                         Sh              Sorghum halepense                                              Ag              Agropyron repens                                               Cn              Cyperus rotundas                                               ______________________________________                                    

                                      TABLE 7                                      __________________________________________________________________________     Com-                                                                               APPLICATION                                                                pound                                                                              Method Rate                                                                             TEST PLANT                                                        No  (kg/ha)  Mz Ww Rc                                                                               Br                                                                               Av                                                                               Dg Al                                                                               St                                                                               Ec                                                                               Sh                                                                               Ag                                         __________________________________________________________________________     14  PRE  1.0 4  3  5 --                                                                               3 4  4 4 3 4 5                                          14  PRE  0.2 3  1  4 --                                                                               4 3  4 1 1 1 4                                          14  POST 1.0 5  2  2 --                                                                               4 5  4 4 5 4 3                                          14  POST 0.2 5  1  4 --                                                                               4 3  1 4 4 4 1                                          15  PRE  0.2 3  2  4 --                                                                               5 4  4 1 1 4 5                                          15  POST 0.2 4  3  2 --                                                                               5 4  5 4 4 4 3                                          16  POST 0.4 4  3  4 4 --                                                                               -- --                                                                               --                                                                               --                                                                               --                                                                               --                                         16  POST 0.2 4  3  4 4 4 4  4 4 4 4 4                                          16  POST 0.1 4  0  4 4 4 4  4 4 4 4 4                                          16  POST 0.05                                                                               -- -- --                                                                               --                                                                               1 4  4 4 4 2 1                                          21  POST 0.4 5  3  4 4 --                                                                               -- --                                                                               --                                                                               --                                                                               --                                                                               --                                         21  POST 0.2 4  3  4 4 4 4  4 4 5 2 1                                          21  POST 0.1 -- -- --                                                                               --                                                                               4 5  4 5 5 2 0                                          22  POST 0.4 5  0  4 4 --                                                                               -- --                                                                               --                                                                               --                                                                               --                                                                               --                                         22  POST 0.2 4  0  4 4 4 5  4 5 5 3 3                                          22  POST 0.1 4  0  4 4 4 4  4 5 4 0 1                                          22  POST 0.05                                                                               -- -- --                                                                               --                                                                               3 4  4 4 4 0 0                                          36  POST 0.8 -- -- --                                                                               --                                                                               4 2  4 3 4 4 0                                          38  POST 0.4 4  3  4 4 --                                                                               -- --                                                                               --                                                                               --                                                                               --                                                                               --                                         38  POST 0.2 4  2  4 4 4 4  3 4 4 4 4                                          38  POST 0.1 -- -- --                                                                               --                                                                               3 4  2 3 4 4 2                                          41  POST 0.4 4  4  4 4 --                                                                               -- --                                                                               --                                                                               --                                                                               --                                                                               --                                         41  POST 0.2 4  2  4 4 4 4  4 5 5 4 4                                          41  POST 0.1 4  0  4 4 4 4  4 5 5 4 3                                          41  POST 0.05                                                                               -- -- --                                                                               --                                                                               4 3  3 3 4 4 0                                          46  POST 0.4 5  4  4 4 --                                                                               -- --                                                                               --                                                                               --                                                                               --                                                                               --                                         46  POST 0.2 5  4  4 4 5 5  4 5 5 5 4                                          46  POST 0.1 5  3  4 4 4 4  4 5 4 4 3                                          46  POST 0.05                                                                               -- -- --                                                                               --                                                                               4 4  0 4 4 4 0                                          52  POST 0.8 3  2  3 3 3 1  3 4 3 4 2                                          52  POST 0.4 -- -- --                                                                               --                                                                               1 1  3 4 3 3 1                                          __________________________________________________________________________ 

We claim:
 1. A compound of formula I ##STR26## wherein: X, which may be the same or different, are independently selected from the group consisting of: C₁ to C₆ alkyl, C₁ to C₆ haloalkyl, C₁ to C₆ alkoxy, C₁ to C₆ alkylthio, halogen, nitro, sulfamoyl, N--(C₁ to C₆ alkyl)sulfamoyl, N,N-di(C₁ to C₆ alkyl)sulfamoyl, formyl, C₂ to C₆ alkanoyl, and the group of the formula --C(R⁷)═NR⁸ wherein R⁷ is selected from hydrogen and C₁ to C₅ alkyl and R⁸ is selected from hydroxy and C₁ to C₆ alkoxy;R¹ is selected from the group consisting of: hydrogen; C₂ to C₆ alkanoyl; benzoyl and substituted benzoyl wherein the benzene ring is substituted with from one to three substitutents selected from the group consisting of halogen, nitro, C₁ to C₆ alkyl and C₁ to C₆ alkoxy; benzenesulfonyl and substituted benzenesulfonyl wherein the benzene ring is substituted with from one to three substituents selected from the group consisting of halogen, nitro, C₁ to C₆ alkyl and C₁ to C₆ alkoxy; and an inorganic or an organic cation selected from the alkali metals, the alkaline earth metals, the transition metals, the ammonium ion and the tri- and tetra-(alkyl)ammonium ions wherein alkyl is selected from C₁ to C₆ alkyl and C₁ to C₆ hydroxyalkyl; R² is selected from the group consisting of: C₁ to C₆ alkyl, C₂ to C₆ alkenyl, C₂ to C₆ alkynyl, C₁ to C₆ haloalkyl, C₂ to C₆ haloalkenyl and C₂ to C₆ haloalkynyl; R³ is selected from C₁ to C₆ alkyl; R⁴ is selected from hydrogen, halogen and (C₁ to C₆ alkoxy)carbonyl; and n is zero or an integer selected from 1 to
 3. 2. A compound according to claim 1 of formula ##STR27## wherein: X, which may be the same or different, are independently selected from the group consisting of: C₁ to C₆ alkyl, C₁ to C₆ alkoxy, halogen, nitro, N,N-di(C₁ to C₆ alkyl)sulfamoyl, C₂ to C₆ alkanoyl and the group of the formula C(R⁷)═NR⁸ wherein R⁷ is selected from C₁ to C₅ alkyl and R⁸ is selected from C₁ to C₆ alkoxy;R¹ is selected from the group consisting of hydrogen, benzoyl and the alkali metals; R² is selected from the group consisting of: C₁ to C₆ alkyl, C₁ to C₆ haloalkyl, C₂ to C₆ alkenyl and C₂ to C₆ alkynyl; R³ is selected from the group consisting of C₁ to C₆ alkyl; R⁴ is hydrogen; n is zero or an integer selected from 1 to
 3. 3. A compound according to claim 2 of formula ##STR28## wherein: X, which may be the same or different, are independently selected from the group consisting of C₁ to C₃ alkyl, C₁ to C₃ alkoxy and halogen;R¹ is selected from the group consisting of hydrogen and the alkali metals; R² is selected from the group consisting of C₁ to C₃ alkyl, C₁ to C₃ fluoroalkyl, allyl and propargyl; R³ is selected from the group consisting of C₁ to C₃ alkyl; R⁴ is hydrogen; and n is zero or an integer selected from 1 to
 3. 4. A compound according to claim 3 wherein:X, which may be the same or different, are independently selected from the group consisting of methyl, methoxy and chlorine; R¹ is selected from the group consisting of hydrogen, sodium and potassium; R² is selected from the group consisting of ethyl, fluoroethyl, allyl and propargyl; R³ is selected from ethyl and n-propyl; R⁴ is hydrogen; and n is an integer selected from 2 and
 3. 5. A compound according to claim 1 selected from the group consisting of:2-[1-(ethoxyimino)butyl]-3-hydroxy-5-(2,3,4-trimethylnaphth-1-yl)-cyclohex-2-en-1-one; and 2-[1-(ethoxyimino)butyl]-3-hydroxy-5-(2,4-dimethylnaphth-1-yl)-cyclohex-2-en-1-one.
 6. A herbicidal composition comprising as active ingredient an effective amount a compound as defined according to claim 1 and a carrier therefor.
 7. A process for severely damaging or killing unwanted plants which process comprises applying to said plants, or to the growth medium of said plants, an effective amount, of a compound as defined according to claim
 1. 8. A process for selectively controlling the growth of monocotyledonous weeds in dicotyledonous crops which process comprises applying to said crop, or to the growth medium of said crop, a compound as defined according to claim 1 in an amount sufficient to severely damage or kill said weeds but insufficient to substantially damage said crop.
 9. A process according to claim 7 or claim 8 wherein the compound is applied at a rate in the range of from 0.005 to 20 kilograms per hectare. 